Used Car Buying Guide

If you’re buying a used car, make sure to check that the check engine light turns on when you insert the key into the 2nd position and the dash lights up. If not, it likely means they removed the bulb to hide a problem.

submitted 6 hours ago by romeomikehotel

Having a friend with or buying a cheap scan tool alleviates this but if you don’t have access to one this is a great way to double check you’re not getting ripped off.

[–]mechapoitier [score hidden] 4 hours ago
Or worse, that the check engine light has been on for so long that it literally burned out the bulb. I've seen a few cars like this.
But yes, unlike that "overinflating the tires" thing somebody posted up earlier, this is a very real, very common trick, and it could hide something very minor or something very expensive.
I actually bought a car that had the oil pressure warning light (the light that, if it comes on, you shut the engine down right now or it will be catastrophically damaged) flicker on for a second, a few miles after I started driving it home. So I shut down the engine as I'm pulling off the side of the road.
Check to see if there's anything obvious, fire it up again and the oil pressure light isn't on and the engine sounds decent, so I keep going.
It turns out that time the oil light flickered on was the last time that light was going to work. The bulb died on my drive home from buying the car, just as the car decided to experience a catastrophic oil pressure loss (from a notorious oil seal that failed on the pump).
The AC was so loud that I couldn't hear the engine begin eating itself. By the time I got home it had eaten all its rod bearings. Knockknockknockknockknock.
I ended up selling that car, that I had bought specifically for the engine, for parts and scrap. Still made money off it.

[–]demize95 [score hidden] 3 hours ago
My father had a car where if it was on an incline, sometimes it would light up the oil pressure light. I'm pretty sure that had nothing to do with the actual oil pressure, just a faulty sensor; the car kept running fine until someone turned out in front of him and both cars ended up totaled. That was a couple years at least after the light started turning on.
That said, were it up to me I'd have gotten the sensor fixed—better to have it working properly than to get used to the light being on and ignore it when it's actually a problem.

[–]zaakystyles [score hidden] an hour ago
It depends on the car. I had a VW bus that has an additional oil sump because of aftermarket oil cooling because of the setup it was possible to cycle all the oil away from the sensor and cause the oil light to go on.
This however is still not good for engine life. Usually means there was no oil in the case to properly lubricate.

[–]ThankYouVeryMuch2017 [score hidden] 18 minutes ago
When the oil light comes on during an incline, or when abruptly stopping/starting, it is most likely due to the oil level being low. When the oil moves around in the pan, the oil pump cavitates briefly, and the oil light flickers due to a brief loss in pressure. In my experiences, you have to be at least 2 quarts low for this to happen.
Source: I'm a mechanic, and have seen this dozens of times.

[–]Jacoman74undeleted [score hidden] 50 minutes ago
My car, 02 xterra, does the same thing on hills, sharp turns, and when braking

[–]ImS0hungry [score hidden] 39 minutes ago
Check your oil level

[–]Jacoman74undeleted [score hidden] 20 minutes ago
oil level is high if anything, I have a leak so I'm regularly adding more.

[–]ImS0hungry [score hidden] 10 minutes ago
High oil level will exsaerbate the leak. It increases the pressure.

[–]AZZTASTIC [score hidden] 18 minutes ago
Im sitting in my 02 Xterra and I have the v6 vg33e engine. I rebuilt the engine in this vehicle and you have to be very careful about oil levels with this engine. Do not overfill it with oil.

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[–]Pvt_Lee_Fapping [score hidden] an hour ago
I ended up selling that car, that I had bought specifically for the engine, for parts and scrap.
Fuck, man...
Still made money off it.
STOP TOYING WITH MY EMOTIONS

[–]DefinitelyHungover [score hidden] 48 minutes ago
that's the nature of flipping cars lol.

[–]Ellis_Dee-25 [score hidden] an hour ago
How do you go about selling for parts and scraps? I have a solid 7.3 powerstroke diesel im trying to part out and dont know where to market.

[–]Stinky_doggo [score hidden] 38 minutes ago
I would check craigslist. I've been looking for a decent 7.3 truck for a while but they're usually all out of my price range - you may be better off selling the truck as a whole.

[–]GarryOwen [score hidden] 34 minutes ago
7.3 powerstrokes are an ecological hazard. I will do you a favor though and take it safely off your hands for free.

[–]sivyan [score hidden] 17 minutes ago
hey its me ur brother

[–]mrchaotica [score hidden] 27 minutes ago
Nice try.

[–]MrMan70 [score hidden] an hour ago
Craigslist might be worth looking into

[–]alltheacro [score hidden] 34 minutes ago
Various online web boards. Google "powerstroke web forum" and knock yourself out. Just make sure to post in the right subsection and follow the rules they've laid out.

[–]rustyxj [score hidden] 16 minutes ago
Is the body nice? I could use a whole new body. Lol

[–]todaysthrowawayfam [score hidden] 14 minutes ago
eBay + diesel shops
Worst case scenario a core buyer will eat up the injectors, turbo, CAT, and anything else still attached (Working or not).
edit: I work at a diesel shop, so not just randomly throwing shit out there btw. FWIW most of the 7.3 stuff is out of production too, so interior stuff is usually pretty sought after (Especially if your seats are nice and cushy).

[–]llewkeller [score hidden] 2 hours ago
Back in the day (60s and 70s), oil pressure lights were notorious for lighting up when nothing was wrong. That's one of the reasons a gauge is better for that function.

[–]RGavial [score hidden] 2 hours ago
Well this was also related to older engine architecture not being able to handle lateral G’s. “Windage” I believe is the term.

[–]obsessedcrf [score hidden] 40 minutes ago
If people pay attention to it. People tend to ignore gauges they don't understand. Red or orange lights are a little more obvious

[–]llewkeller [score hidden] 11 minutes ago
My otherwise great car - a Mazda3 - deleted the temp gauge. I get a blue light when the engine is cold, and have never seen the red overheat light. But the advantage to gauges is that you can be aware of whether or not your car is in danger of overheating by how far and how high the needles goes. If it goes up fast, and is riding in the top 1/4, a problem may be developing. You can't do that with warning lights.

[–]rustyxj [score hidden] 14 minutes ago
Unless you drive a trailblazer, it has a gauge, when you accellerate the gauge goes up a little, just like a real oil pressure gauge. At idle the gauge reads around 40psi, in actuality, the engine is putting out around 15psi at idle.

[–]Agentreddit [score hidden] 49 minutes ago
What car was this?

[–]thenetkraken [score hidden] 17 minutes ago
Feels like a subaru.

[–]alltheacro [score hidden] 35 minutes ago
And that's why I'm thankful for my state's lemon laws on cars.

[–]punkerster101 [score hidden] 8 minutes ago
My wife was driving around with no oil in her car for months before she told me the oil light was on. Seal at one of the sensor points had broke every time the engine heated up it spewed oil all over the engine...
£3 part a YouTube video and some oil and it’s been 6months and it seems to be running fine...

[–]01Triton10 [score hidden] 3 hours ago
Remember to make sure the vehicle wasn't purchased in the southern states then suddenly appeared in the northern states for sale since the recent floodings. This has been a recent occurrence.

[–]jlmbb [score hidden] 2 hours ago*
A mechanic told me you always check where the spare tire is to see if there's any discoloring from dirty water. For some reason, they never look at that area to clean.

[–]gweilo8888 [score hidden] 40 minutes ago
Also, pull out all inertia reel-style seatbelts to their maximum extent and see if the end of the belt is damp, discolored or water-stained.

[–]voonoo [score hidden] an hour ago*
What if the car doesnt have a spare?!?!?!
Edit: to the asshole that downvoted me, some newer cars don't come with spares.

[–]chikknwatrmln [score hidden] 41 minutes ago
There is usually a toolkit under the false floor - this area would probably show evidence of flood damage if not cleaned

[–]BrookeBasketcase [score hidden] 22 minutes ago
My 2015 chevy spark literally doesn’t have a place to put a tire. I 2nd this. My car has a tire repair kit and the number for a tow truck 😒

[–]SirLaxer [score hidden] 19 minutes ago
Same goes for my dad’s new Volvo.

[–]vizualkriminal [score hidden] 23 minutes ago
It'll be easier to check that area

[–]creamydick [score hidden] 55 minutes ago
I've been hearing this a lot lately. How far back should this tip apply? We bought a used vehicle in Virginia that was from Florida back in December. There wasn't anything on the Carfax report.

[–]chunkymonk3y [score hidden] 51 minutes ago
OP is referring to the current series of storms that have hit the south (Harvey, Irma) which happened at the end of this summer so it doesn't apply to you

[–]creamydick [score hidden] 48 minutes ago
Good to know! Thanks!!

[–]wskv [score hidden] 24 minutes ago
When I was in my early twenties, I bought a used Corolla in Oklahoma. After suffering through lots of small issues that seemed coincidental at first, I did some digging after a major engine failure. Turned out that the Corolla was registered in Louisiana during Katrina.

[–]rustyxj [score hidden] 13 minutes ago
I'd be more than happy with a water damaged 7.3 super duty or a 91-01 Cherokee.

[–]Lomanman [score hidden] 5 hours ago
Make them come to an auto parts store that will scan for free.

[–]0ddmanrush [score hidden] 2 hours ago
Or just buy your own for $15 on amazon.

[–]angrygnomes58 [score hidden] 2 hours ago
Then charge your friends who refuse to buy their own $5 per scan. Owning a scan tool is one of the easiest ways to save money on car maintenance. A lot of the codes are pretty straightforward. If you have a scan tool that connects to a phone app often times it has either further details or a link to do an internet search on the code and what it may mean.

[–]453265436354654 [score hidden] an hour ago
Auto parts stores don't charge to scan so I'm not sure I'll save much money at all.

[–]IssuedID [score hidden] an hour ago*
In some states they do.
edit: downvotes for truth? lol ok

[–]crashddr [score hidden] an hour ago
California is one of the states where Autozone can no longer provide free scans. IIRC this is because individual shop owners complained that they couldn't rip people off anymore or something. At the time, I think the law on this was new, and I purchased my OBDII scanner at a significant discount.

[–]IssuedID [score hidden] 55 minutes ago
Hawaii is another one.

[–]Urakel [score hidden] 24 minutes ago
Still have to drive there, sometimes it's too far, or they're closed.

[–]polopollo85 [score hidden] an hour ago
As someone who purchased his first car 2years ago, I need to learn all that. What is this app, and what kind of cable is that on amazon?

[–]U_Buttonhooked_Me [score hidden] an hour ago
OBDII Bluetooth Scanner, and an app like this one.

[–]angrygnomes58 [score hidden] 59 minutes ago
Torque is my favorite scanner app as well.

[–]gweilo8888 [score hidden] 21 minutes ago
Or maybe don't be a dick to your friends, and scan the code for free. I'm sure they've bought you drinks or something, sometime, which cost more than your scanner (which can easily be bought for less than the cost of a single bottle of beer at a typical bar).

[–]haffa30 [score hidden] 21 minutes ago
Do these scanners work on older cars?

[–]BDMayhem [score hidden] 9 minutes ago
Depends on the age. OBD-II became a standard in the mid-90s. Before then, there may be some diagnostic info, but it may not have as much information as newer cars.

[–]Zcypot [score hidden] an hour ago
I been hearing a lot that they dont do that in autozone anymore. My friend got turned away when she tried getting a code read.

[–]ChosenServant [score hidden] an hour ago
Around here, both O'Rielleys and Autozone do it for free.

[–]Bureaucrat1 [score hidden] 29 minutes ago
Depends on the state some people said. Just call and ask, or buy a $5-10 one yourself.

[–]deutsch-technik [score hidden] 9 minutes ago
Piggybacking on this comment, if you're looking to pull the codes on luxury/high-end cars, most generic OBD2 scanners will not be able to detect manufacturer-specific faults. For instance my Autel scanner that I picked up from Amazon for $15 is pretty useless when it comes to both of my cars. However my more expensive icarsoft scanner will pull both generic and manufacturer specific codes, and works perfectly with my cars.
This means that if the scanner cannot detect certain codes, it can appear that the car is completely fine.

[–]SaveToTheADrive [score hidden] 3 hours ago
Unplugging the battery on some cars will also prevent the check engine light from going on until several miles have been driven on it, or enough time has passed.
Just go to AutoZone on your test drive.

[–]Knary50 [score hidden] 2 hours ago
What you actually want to check is the OBII Readiness. I think that's what it is called. It will show you that the battery has been connected long enough for the cycles to run that would trip the light. Better off scanning yourself than taking the word of a parts store clerk as you never know what their actual knowledge is.

[–]pm_me_construction [score hidden] an hour ago
Agree. Bought one of those orange code scanners for like $75 on Amazon. Probably the best tool I’ve ever bought.

[–]Fuel13 [score hidden] an hour ago
or you can get a bluetooth one on ebay for less than $10 and scan with your phone.

[–]53bank [score hidden] an hour ago
You mind providing the name of a good one? I'd like to grab one if possible from eBay. Thanks in advance

[–]OmniQuestio [score hidden] an hour ago
Not op but, For app, I use Torque Pro. Bought years ago and they still update it regularly. I guess you can use the free version too.
They have a list of obdII adapters that work well with the app, look it up.

[–]fraxinuscavum [score hidden] 53 minutes ago
I second Torque Pro. My adapter was more like 150 bucks about 4 years ago, but it was fully worth it. Had an android stereo by parrot so I got all my realtime info on the screen. Good stuff!

[–]GET_OUT_OF_MY_HEAD [score hidden] 44 minutes ago
Also, ignore that list. They want you to buy a $45+ adapter when the $10 Chinese ones work just fine.

[–]hard_boiled_rooster [score hidden] 36 minutes ago
You can also use the torque pro app to clear your check engine light

[–]_jumpstoconclusions_ [score hidden] an hour ago
Not OP but I ordered this one on amazon: https://www.amazon.com/gp/product/B074DW7T5T/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1
I actually received this other brand instead but it works so I don't mind at all and I highly recommend it:
https://www.amazon.com/Viecar-Bluetooth-Vehicle-Diagnostic-Android/dp/B07211Y6JJ/ref=cm_cr_srp_d_product_top?ie=UTF8
Here is the review I provided, which you can read on the product page as well of course: "I felt I needed to provide a review in the hopes that my experience may be helpful to other people. I placed an order for this item (the LITOON scanner) but what I received instead was one manufactured by Viecar, so I am a little conflicted as to what to rate this device since I received a different one from the one I ordered. When the device arrived I downloaded some apps which I read were compatible (thinking it was the LITOON scanner). I need to point out that I have an older Iphone 5S with iOS 10.3.3. After plugging the unit to my car (a 2000 VW Jetta) and starting up the apps with no luck I finally decided to take a look at the instruction booklet provided with the device. There are 3 apps listed there for the Iphone: GeekOBD_Viecar (free), Mini OBD II(free), and OBD Fusion($9.99). I downloaded and tried the first two apps since I wasn't about to pay $9.99 if I couldn't get it to work with those two. I didn't have any luck with "GeekOBD_Viecar, it just wouldn't connect; which is really lame especially since they make you register before being able to try it. The second app, MIni OBD II didn't have a problem connecting (I had to register as well) but the info provided was sparse; I was able to use it to clear an error code and turn off my check engine light which was a plus! Since I saw that that app worked I decided it may be worth forking over the $9.99 to try the OBD Fusion app. That one worked like a charm, connects a lot more easily (once I figured out I needed to go into the settings in the app to switch from wifi to bluetooth). I haven't played around with this last app otherwise but it seems lot cleaner and customizable.I think you can get by with the free Mini OBDII app but to get the most out of it. In summary I recommend if you are looking to get this make sure you clarify which scanner you will receive (the LITOON vs the Viecar); or to make sure you do get the Viecar look elsewhere (hint, it's also on Amazon). To clarify I am not affiliated with any of these products (scanner or apps)."

[–]onji [score hidden] an hour ago
Question. Do these drain your (car) battery when left plugged in all of the time?

[–]_jumpstoconclusions_ [score hidden] 54 minutes ago
The specific one (Viecar) that I bought didn't seem to have any effect on my car battery. I left it plugged in since I bought it a few weeks ago and haven't noticed any drain.

[–]Urakel [score hidden] 26 minutes ago
I forgot one plugged in for a couple of months, didn't cause any trouble. It doesn't start unless you turn the key though, so there's probably no need to worry about it.

[–]CourseHeroRyan [score hidden] an hour ago*
I have a handful of ELM327 OB2 readers from ebay. $3 about, or less. Stupid cheap, they just act like a fancy USB cable and send the data over bluetooth. Paying more than $5 unless you need it fast is stupid.
At that point, it comes down to your app handling the data, and as someone else mentioned, torque pro is solid.
Edit: $2
http://www.ebay.com/itm/Super-Mini-OBD2-OBDII-ELM327-V1-5-Android-Bluetooth-Adapter-Auto-Scanner-Torque-/262838256834?hash=item3d326184c2:g:kRkAAOSwLEtYltV3
All these other models people are paying $10-15 for have no different functionality. There are wifi ones for iOS, which use to cost $20, which is what I have. Bluetooth is better for this scenario IMO. US companies will do BLE because then they can write their own protocol without going through apple's bullshit bluetooth certification that they have on regular bluetooth to use stuff like a serial port over bluetooth. I'm not sure if there are cheap chinese bluetooth adapters with their own protocols that are iOS compatible, its been a while.
Edit: The cheapest Bluetooth ELM327 adapters are likely NOT iOS compatible. I just want to make that clear. It's been years since I've purchased one, Wifi models now cost <$10, but if you can get bluetooth, some advertise bluetooth and iOS compatible and <$10.
If you buy it, and it says it is iOS compatible, but it turns out it isnt, complain to support. The seller may try to negotiate and give you $1-5, but just escalate the situation and eBay will always refund you 100% of your money for something like that.

[–]hard_boiled_rooster [score hidden] 29 minutes ago
Ya I've had an elm327 for about two years now. Does exactly what you need it to with torque pro

[–]frugalerthingsinlife [score hidden] an hour ago
Amazon is probably cheaper for the same unit. I bought a few for myself and family members. You don't need a 'good' one. They all work. Also, spend a few bucks on the Torque app.

[–]Notwhoiwas67 [score hidden] an hour ago
PLX is a decent brand.

[–]C0rdt [score hidden] 53 minutes ago
They are all the same. And like the other guy said use torque pro app with it.

[–]hard_boiled_rooster [score hidden] 35 minutes ago
Just get a cheap Chinese one for $10 off Amazon. They do exactly what you want them to do. I've had the elm 327 cheapo blue tooth adapter attached to my my car to run torque pro while I drive for 2 years now.

[–]Darkstrategy [score hidden] 50 minutes ago
Would this work with old cars? Like my 2000 Subaru?

[–]livinbythebay [score hidden] 29 minutes ago
Research if it uses OBDII standard. My 98 4runner does no problem.

[–]hard_boiled_rooster [score hidden] 28 minutes ago
Does your car have an obdII port?

[–]hotizard [score hidden] 15 minutes ago
Yes, depending how old. I'm not sure if ELM327 is compatible with the original OBD(I) standard. If I had to guess, I figure it would be.
Wikipedia states,
1996: The OBD-II specification is made mandatory for all cars manufactured in the United States and sold in the United States.
That snippet is unclear if all vehicles sold under the 1996 model year have OBDII, but it will definitely work on your 2000 Subaru. I used one of those Bluetooth scanners on mine.

[–]Darkstrategy [score hidden] 14 minutes ago
Thanks for the info, appreciated.

[–]tossoneout [score hidden] 48 minutes ago
vote this to the top
I bought extras when I found them on ebay for two dollars and give them away

[–]travelinman88 [score hidden] 17 minutes ago
I spent $20 on an adapter and use the free app.
obd II bluetooth reader

[–]Whiskey_Rain [score hidden] 52 minutes ago*
You're very close. They're called "Readiness Monitors" or just monitors in the biz. The ones you want to pay close attention to are the catalyst and heated o2 monitors. Those are the ones that take the longest to set and almost a sure fire way to tell if the computer has been reset in the last ~100mi.
Unfortunately car sellers can be dirty and hide problems that only the most savvy car buyers will know to look for. However, armed with the right knowledge you can certainly limit your exposure to risk. Always trust your gut.
And when in doubt find a reputable Indy to do a PPI! A good Indy wants your business and will generally do a much more thorough job than a dealer!
edit: +1 on the Bluetooth obd2 dongles. They're an indispensable tool if you own a car. As far as apps go, Torque lite is popular, I happen to like the interface of OBD Fusion more, but it's up to preference. They both do the same thing.

[–]ThomasButtz [score hidden] 2 hours ago
Yep, or just buy a $19 bluetooth OBDII reader off amazon and download torque lite app. I consider it an essential item in my toolkit on road trips.
IMHO, if you don't have the financial resources to buy a car with a solid warranty, you should invest your time in educating yourself on basic car knowlegdge. Being an informed consumer has value.

[–]alltheacro [score hidden] 30 minutes ago
Or take it to a mechanic the seller doesn't know, and have them evaluate the car doing a prepurchase inspection.

[–]Donokage [score hidden] an hour ago
Before you get there, do a google of the OBD drive cycle for the vehicle. While you are test driving, do the things on the list (it's usually stuff like accelerate to 60mph then coast at 45mph for 2 minutes etc.) This will let the computer check for problems and present new error codes if they have been cleared by disconnecting the battery. That way, the scanner has something to read. (Source: SMOG check guy when I bought a car with a dead battery.)

[–]Notwhoiwas67 [score hidden] an hour ago
Or spend $10 on your own code reader.

[–]Notten [score hidden] 2 hours ago
Had someone do this to me. Luckily it was only the gas cap sensor saying it wasn't closed. Things could have been way worse but it's the nicest car I've had yet.

[–]pm_me_construction [score hidden] an hour ago
Just an FYI: There isn’t a sensor on the gas cap. The code that comes up if the gas cap is leaking is a vacuum leak. Ordinarily the engine produces a vacuum effect. The vacuum is required in order for the engine to run correctly and is also used to reduce emissions.

[–]Deltigre [score hidden] 30 minutes ago
A normal vacuum issue will trigger a different code than the gas cap. Usually the gas cap triggers an evaporative emissions code.

[–]ArrivesLate [score hidden] 8 minutes ago
I think the Subaru I had actually had an ignition count before it would display a check engine. I think it was 6 or so.

[–]Slipalong_Trevascas [score hidden] 4 hours ago
Much better to scan it.
It is more likely they will wire the check engine light across to the oil pressure light. That way it comes on before start-up but not while the engine is running.

[–]JoeyJoeC [score hidden] 2 hours ago
I drove 800 miles to buy a car. Everything looked fine and in order, fuel was low but the seller insisted he will fill it up after our test drive. We drove it a couple of miles but it was really about to cut out at any second so we drove back, agreed to buy it, made the sale (guy was over welcoming, made us tea and gave chocolate etc).
He then fills it up enough so we can go to a garage, we then filled it up, stayed overnight nearby in a hotel, and then drove home the next day. Literally a couple of miles from our house, I noticed something leaking from it, we later found there was a large hole in the fuel tank that had been stuffed with plastic bags and silicone.
We were almost ripped off, except that the car happened to have a rare super charger fitted to it that we managed to sell for more than the price of the car, we fixed the car and made more than the original sale again.

[–]frog_milk [score hidden] an hour ago
Heck yeah, that's awesome!!

[–]rustyxj [score hidden] 11 minutes ago
What supercharger is that rare?

[–]cintecian [score hidden] 3 hours ago
There are a ton of ways to be scammed in a private auto sale. The seller can clear the codes if they have a scanner. On most cars this should probably induce its own code to show that it was cleared recently. Something to look out for. Also I’ve seen seller disconnect the diagnostic port altogether and claim ignorance. Open the hood and it looks like they used armor all on everything? Chances are seller is trying to hide a leak. Don’t be afraid to get under the car to look for leaks. Visually inspect the gaps between body panels and run your finger over them as well. A sudden gap or narrow area between panels means body damage and possible frame damage. The list goes on and on.

[–]joeChump [score hidden] 34 minutes ago
Yeah, this is true. Check for a cleared code which indicates that they have hidden a problem. Could be genuine though like there was a problem and it got fixed so they cleared the code. ChrisFix has a great series on YouTube about checking out a used car from phoning the seller to test drive to negotiating sale. Lots of great info in it and he does it in a real life scenario as he's buying an actual used car. Best I've seen.

[–]romeomikehotel[S] [score hidden] 5 hours ago
The best way to avoid this is to buy one of the cheap Bluetooth scan tool on eBay for around $14 and download one of the many apps that will Check diagnostic codes through the scan tool.

[–]polopollo85 [score hidden] an hour ago
Any youtube video? I'm totally noob on that

[–]WellTimedPoop [score hidden] an hour ago
Not sure about a youtube video (i'm sure a million exist and I could probably find one quicker than it'll take me to type this), but it really is dead simple. When you get the OBD 2 plug (just google OBD 2 bluetooth and buy the cheapest one on amazon), plug it in to the slot in your car (any car newer than '96 will support it), download Torque Lite (or whatever the iOS equivalent is), pair the devices, and you're up and running.

[–]Pyronic_Chaos [score hidden] 15 minutes ago
If you can't find your OBD2 plug in slot (required on all US cars post 1995 I believe), it should be somewhere right around the driver's area. above the pedals is one place, off to the left by the door is another. Otherwise, just Google "OBD2 location [Year] [Make] [model]"

[–]DarthAnalBeads [score hidden] an hour ago
Not a video but detailed instructions from the last time this was posted, hope it works!
https://www.reddit.com/r/LifeProTips/comments/4aldqz/lpt_when_purchasing_a_used_car_make_sure_the/d11h4be

[–]blarrick [score hidden] an hour ago
Always bring a scanner if you're checking out a car. $15-20 on Amazon with Prime shipping. The reason is not only for what OP stated, but those tools can also turn off the check engine light. I believe you need to drive around 10-20 miles for it to come back on (if the issue is still there), so if the salesman turned the light off and parked the car, you can turn the key to position 1 and the light will turn on, yes, but when you start the engine it won't turn on even if there is still an issue.

[–]Notwhoiwas67 [score hidden] 58 minutes ago
I believe you need to drive around 10-20 miles for it to come back on
Depends on the issue. Some take a certain amount of driving, some take a certain number of start cycles and some are pretty much immediate. Most of the time the "your engine is about to die" ones are pretty immediate.

[–]joeChump [score hidden] 40 minutes ago
True. But the point about them switching the lights off is totally valid. Every time I check out a used car business by reading reviews online there is always someone who puts "an engine light came on the next day/on the way home so I had to take the car back for them to look at," and I think, yeah, I wonder why that engine light suddenly came on straight after you bought it...

[–]Notwhoiwas67 [score hidden] 30 minutes ago
True. But the point about them switching the lights off is totally valid.
Totally. All I was doing is clarifying that the light coming back on in 10 to 20 miles isn't really the whole story. You could, for some faults, drive the thing 200 or more miles and not have the light come back on until you had stopped and started the engine several times.


[–]DarthAnalBeads [score hidden] an hour ago
You can also check this post for useful info
https://www.reddit.com/r/LifeProTips/comments/4aldqz/lpt_when_purchasing_a_used_car_make_sure_the

[–]godamnsamsquanch [score hidden] an hour ago
TIL: When selling your car, remove the check engine bulb and over inflate the tyres.

[–]Warrenwelder [score hidden] 46 minutes ago
I removed the tires and overinflated the check engine bulb. Checkmark car-buyers.

[–]luouixv [score hidden] 3 hours ago
Are used car sellers not liable if the buyer did find that the bulbs had been removed?

[–]romeomikehotel[S] [score hidden] 3 hours ago
No used sellers are liable for almost nothing. You buy a car as is so whatever the case may Be you’re stuck with it. Which is why pre purchase inspection is super important if you don’t know what to look for.

[–]Knary50 [score hidden] 2 hours ago
Sort of, check local laws. Here a CEL will not allow it to pass emissions. By law if the buyer lives in a county that has emissions the seller is responsible for repairs so it can pass. This may only apply to dealers and not private sales. But overall you should assume any repairs will he the buyers responsibility unless you have a written warranty or its in the contract / bill of sale.

[–]davidquick [score hidden] an hour ago
If you could prove intent then maybe but in general I think this would be difficult to prove.

[–]larrieuxa [score hidden] an hour ago
i see this post 2 weeks after i already bought the used car. godammit.

[–]frog_milk [score hidden] an hour ago
same man... same...

[–]System0verlord [score hidden] 44 minutes ago
Also same

[–]cryospam [score hidden] 4 hours ago
Or spend the 15 dollars and buy a code scanner...

[–]a22e [score hidden] 2 hours ago
Buying a cheap scanner to check for codes is best.
Even then you will want to drive it up and down the road a few times completely shutting the car off between trips. Some codes take several key-cycles to set.
Also if it has an intermittent code it could take days to set again. A high-end scanner can tell you how long it has been since the codes were last cleared on newer cars. I have seen so many cars from used dealers set a light within a week of purchase. They clear them until it's your problem.

[–]DoomDoomyDoom [score hidden] an hour ago
That is just evil. Luckily in a BMW you'd probably have to remove the engine, shift the oil resevoir over, jack it up and dislocate your your shoulder just to reach the bulb.

[–]Morrissey_Fan [score hidden] 28 minutes ago
Nah, a couple screws and I was able to replace a bulb in my X5's instrument cluster.

[–]ZombieLinux [score hidden] 35 minutes ago
Additional protip: Check the radio presets. If NPR is on one of the presets, the odds of the car having been maintained are much higher.

[–]ojazer92 [score hidden] 3 hours ago
Just get a complete mechanical inspection from a mechanic you trust...

[–]musketeers [score hidden] 2 hours ago
Make sure you kick the tires before or after the test drive.

[–]mrdctaylor [score hidden] an hour ago
You can get a OBDII scanner for under $20 online and can google the codes (if any) quickly from your phone.

[–]Kytoaster [score hidden] 41 minutes ago
Or just pull the codes? You can get bluetooth obdII readers that link do your phone for like $15 on amazon. No excuse to not check for cleared and current codes on a used car anymore.

[–]Desert_Rat1294 [score hidden] 19 minutes ago
On some vehicles it is possible to get the code without a scanner and look it up on your phone. For example on a 2008 ram 1500 you turn the key to the 2nd position 3 times. On the 3rd time leave the electrics on and the code will display in the odometer.

[–]thatdethmetalguy [score hidden] 2 hours ago
Or they could do what I do to get my beater to pass inspection and force the code to clear so there is no reason for it to light up.

[–]HereForTheGang_Bang [score hidden] an hour ago
Many stations won't run an inspection while it's still in learning mode, which would mean they'd tell you to go drive more and get more cycles. Likely the light would come back on.

[–]Notwhoiwas67 [score hidden] 55 minutes ago
Many stations won't run an inspection while it's still in learning mode, which would mean they'd tell you to go drive more and get more cycles.
This would be a sure sign that the seller recently cleared the codes.

[–]fear_and_loafing [score hidden] an hour ago
So, I'm probably going to be in the market for a used car soon. Any other LPT or recommendations to other threads/information elsewhere?

[–]todaysthrowawayfam [score hidden] 35 minutes ago
If you have around $100 bucks to spare just have it inspected. I work at a diesel repair shop and it's a pretty common occurrence for us. Worst case scenario you spend the money and then get it back with bargaining power because there are issues with the vehicle, best case scenario you spend the money and get some piece of mind knowing the vehicles in solid shape. The honest dealerships will already have this done by a third party, but I know those are pretty rare. A good example of why you would want to do this, last week we inspected a Jeep that was exceptionally clean with decent mileage on it. Once we had it up in the air on a lift though you could see botched welding from a backyard oil pan repair. It's definitely worth the time and money.

[–]fear_and_loafing [score hidden] 32 minutes ago
That's actually something my parents used to do! Thanks!

[–]AgentKuma [score hidden] 9 minutes ago
Please just get it inspected and skip all the 'tricks' in this thread.

[–]joeChump [score hidden] 2 minutes ago
Check out the ChrisFix series on YouTube. Takes you through a real used car purchase from start to finish. Very useful info and prob the best I've seen. It's useful to see in video because he shows you examples of really bad stuff or things that wouldn't be a deal breaker. A checklist is good to take but most checklists tell you what to watch out for but not how serious a problem each item is. ChrisFix is good at putting it into perspective and the walk-through is invaluable.
https://www.youtube.com/playlist?list=PLvKbarVtwhUv6bjLhJSyaEOxaYy03j7QS

[–]_josepi_ [score hidden] 2 hours ago
That's why you need a spdt relay with a feed from the alternator circuit. Pass power until feed breaks signal from the battery to the light, once car is on, no more light.

[–]Ramys [score hidden] an hour ago
I've seen a more dangerous version of this with airbags. After they go off, some mechanics will simply remove the airbags and play with the wiring to trick the onboard computer into thinking new airbags have been installed.
Saves them money on repairs, but won't save a guy's life if it crashes again.

[–]tggrinc1st [score hidden] an hour ago
I worked at a new car dealership in the early nineties where this was standard operating in procedure for any used car with the light on.
I'm sure it still is in many places, especially the small independent junk lots that buy auction cars for resale.

[–]rwbombc [score hidden] an hour ago*
Yeah or just buy an ODB-II adapter for $3 off eBay (cheap Chinese mainland trash but works) download an app (sometimes $5, sometimes free) and check it yourself pretty much forever and on your own car.
You can even turn off the CEL if the problem is minor yourself with it. I did it the other day-really minor problem that won't effect driving, just testing that I won't get fixed until inspection next may.

[–]starry177 [score hidden] an hour ago
I'll wait for the unethical pro tip for this.

[–]Forlarren [score hidden] an hour ago
Shit, just saves me the trouble.

[–]amgrrrr [score hidden] an hour ago
Also, look for black electric tape or nail Polish over dash lights. It sounds stupid, but I have seen it done firsthand. :(

[–]erictho [score hidden] an hour ago
I hired a broker to find us a car since at the time i couldnt drive and just needed something, almost anything, that was dependable. There are so many crappy dealerships i didnt even know how to approach finding one. Got a 2013 kia rio with only 43000km on it before we got it. Sure it was once a rental but it was maintained after every time it was borrowed. Only have had to get winter tires and new windshield wipers in the almost 3 years i have had it. Worth every penny of hiring a broker for $650

[–]HereForTheGang_Bang [score hidden] an hour ago
Or they're smart like I was when I had to get an inspection and wired the bulb to the oil pressure light so it'd come ok with the key but turn off once started..

[–]Vapeyourself [score hidden] an hour ago
I had an 02 GT that always had the check engine light on because of a bad rear o2 sensor. I got tired of looking at it and pulled the bulb. However for thought of this and made it so if the bulb is broken or not in place it constantly dings at you. So I just painted the bulb black and put it back in.

[–]DoubleX [score hidden] an hour ago
This happened to me, but it was the airbag light. Luckily I didn’t learn the hard way that my car did not have functioning airbags.

[–]KawiNinjaZX [score hidden] an hour ago
If you or someone you know doesn't know much about cars, just get a pre purchase inspection done, for like $100 you can have piece of mind.

[–]mad_lithuanian [score hidden] an hour ago
TIL there's a bunch of sneaky mofos out there.

[–]Intense_introvert [score hidden] an hour ago
Or you know, just take the car to a shop for a pre-purchase inspection. It's $100 well spent.

[–]therealrenshai [score hidden] an hour ago
Better yet if you're buying a used car take it to autozone (they do it for free) or a mechanic you trust to do a quick scan to see if trouble codes have come up.

[–]Apocalypse487x [score hidden] an hour ago
OBDII reader helps find other faults. Used that to find out that the drive train had 3 major issues on a used car.

[–]AeroUp [score hidden] an hour ago
Just test drive it, and take it to AutoZone for the free, ‘onboard computer check’. They plug in a thing and check system faults.

[–]InteriorEmotion [score hidden] an hour ago
Years ago I had a car with a check engine light that refused to describe, no matter what repairs I tried. Eventually I had no choice but to remove the bulb, burn it out, and put it back.

[–]pTomic [score hidden] 58 minutes ago
Also check engine oil color and check if engine burning oil...

[–]ride365 [score hidden] 56 minutes ago
Also, check that the tires are properly inflated.

[–]corporaterebel [score hidden] 50 minutes ago
Worse: they spliced the MIL light in line with another light (SRS/Brake/etc...) and it appears to operate (burn-in) as normal.
Get a code reader for any OBDII car, you can buy them on aliexpress for $3. Difficulty: SRS and ABS tend to have their own computers as well.
If OBD/OBDI then you will have do research on your particular model of car to read the codes. Each one can be different.

[–]inu_yasha [score hidden] 50 minutes ago
Don't forget to check under the vehicle as well. I just bought a car, from a mechanic, that had two torn cv boots. After I paid for it, he also let slip that he drove around in power mode 100% of the time and snow hold every time it rains. Cant wait to find what damage that did to the tranny and dif.

[–]kevin_with_rice [score hidden] 49 minutes ago
So the check engine light is supposed to be on at the second turn? I thought something was wrong with my car

[–]mrcranz [score hidden] 49 minutes ago
turn the key slowly forward, usually in between the RUN and START position there is a bulb check spot which will make the dash illuminate all the bulbs to make sure they are all working. it’s different on every car but if you do it slowly it should show up for you.

[–]thatshitsfunny247 [score hidden] 46 minutes ago
You can also buy a $20 adapter and clear check engine light codes yourself.
So just buy one of those and bring it with you, and plug it in before walking away.

[–]IvaNoxx [score hidden] 45 minutes ago
Also, check order in which lights are going away. Make sure they are not "going away" at the same time. That means one thing. Something was "connected" with something so light comes up and goes away with it.

[–]kylexy51 [score hidden] 45 minutes ago
They typically won't take out the bulb, it's much easier to just reset the code by disconnecting the battery then reconnecting it.

[–]MaxStout808 [score hidden] 43 minutes ago
This one turns itself into an unethical life pro tip pretty easily.

[–]RickyWicky [score hidden] 43 minutes ago*
I bought my car with the engine light burning sporadically. Had it checked out multiple times and no one can find a problem with their magic diagnostic machines; some have poked around inside the engine, also can't find an issue. If there is an issue, it doesn't seem to be major, because the car hasn't given me any problems since I've had it. So, I've accepted the light the comes on when it feels the fuck like it.
Edit: some words.

[–]LoneCookie [score hidden] 37 minutes ago
This sounds like it should be illegal...

[–]oneXoneallday [score hidden] 36 minutes ago
My check engine light has been on since changing my spark plugs and engine filter by myself last year and my mechanic cannot find a problem. How fucked am I?

[–]mustanggt90210 [score hidden] 35 minutes ago
Good tip!
My truck has a burned out or removed CEL, as well as a taped over airbag light. Didn't know either when I bought it. Thankfully it has caused me no issues, but it was a concern when the truck started running terribly a year later. Plugged in a code reader, got codes, and that's when I realized the CEL didn't work lol

[–]StewHax [score hidden] 35 minutes ago
The best thing you can do is test drive it for a bit - you an easily reset things like that by disconnecting the battery for a short time and then the engine light will take a while to come back on. Wouldn't hurt to also buy and ODBII reader as well just to be sure

[–]smokeandfog [score hidden] 34 minutes ago
Also using an OBD II scanner to check if there are any engine problems is a good way to “check what’s under the hood”
Source: I’m a Smog Technician

[–]doubleflusher [score hidden] 32 minutes ago
Step 1. Use OBDII scanner.
Step 2.????
Step 3. Profit

[–]jondoelocksmith [score hidden] 31 minutes ago
Seriously, OBD2 bluetooth scan tools are $15 on amazon, and can be read on your phone for advanced features. No excuse to buy a running car without a scan.

[–]GreenWeiner [score hidden] 31 minutes ago
A lot of newer cars use LED's soldered directly to the board instead of bulbs, thus making it more difficult to disable the light without damaging the instrument panel circuit board, and less likely to be tampered with. If you are really concerned, bring your own scanner and explore the entire recent code history! Little bluetooth scanners can be bought cheaply, just make sure the obd version of your target vehicle matches the cheapo scanner. The CEL history is a strong negotiation token when buying a used car...

[–]Bobmaloogalooga [score hidden] 29 minutes ago
1980's tips. Most are now LED and part of a larger display. OBDII tools are dirt cheap, some even <$10 and work over bluetooth to your phone.

[–]shinicle [score hidden] 27 minutes ago
The real LPT: if you selling a used car with a shit engine, don't just disconnect the check engine light. Instead, connect it to the oil light so that it lights up when the key is in second position.
This also works with e.g. broken braking systems.

[–]GODAMA [score hidden] 27 minutes ago
I'm not sure how much of a real tip this is, if you're looking for a car built after 2010 or 2012 taking apart the dash to pull the light can be a huge pita.
On the other hand owning a OBD2 scanner (to diagnose check engine lights) is kind of Priceless, cheap to buy and will last forever

[–]recommendmeapodcast [score hidden] 27 minutes ago
Holy shit reddit thanks for convincing me never to buy a used car.

[–]AfraidOfAtttention [score hidden] 25 minutes ago
Bring an OBD reader, they're infinitely useful and can relieve a lot of maintenance anxiety if you know the problem is relatively small

[–]night-shark [score hidden] 24 minutes ago
Extra LPT:
Buy yourself a $30 bluetooth OBDII reader from Amazon. Get a reader app for your phone. Plug that sucker into the car and call up all codes (including pending codes).

[–]heyitsbobandy [score hidden] 21 minutes ago
Isn't the check engine light part of the ignition circuit for cars?

[–]MicroscopicFruition [score hidden] 18 minutes ago
Thanks for the tip!

[–]cdegallo [score hidden] 18 minutes ago
ULPT: If you're selling a car that has a check engine light warning, remove the bulb so the buyer won't know anything is wrong!
r/unethicallifeprotips

[–]SirAttackHelicopter [score hidden] 15 minutes ago
If you're worried about a check engine light, chances are that car is on the old side of things, and replacing every single component that is marginally out of spec but perfectly safe, is totally not worth it.
For example, an O2 or MAF sensor is a common one I've seen for my vehicles. The ECM will simply take those readings and compare it to defaults, and if the defaults are better, it will use them instead. The difference is literally unnoticeable.
FYI A check engine light doesn't show the important issues of the vehicle, that is why all "other" errors are grouped together with 1 light code. Keep the car lubed and fueled, keep up the standard maintenance, and check the tires.

[–]g2g079 [score hidden] 13 minutes ago
Also you can unplug the battery for a bit to temporarily get rid of the light in some vehicles.

[–]orlandofredhart [score hidden] 13 minutes ago
/UnethicalLPT if you're selling a used car remove the check engine light ot hide a problem.
It makes me sad that people actually do this

[–]Nicko1092 [score hidden] 13 minutes ago
LPT: if you need a LPT to know this trick get someone who knows more about cars to come with you to check over the car.
Added bonus: They won't be excited at the prospect of possibly buying that car, will be calmer and take a measured approach to the value and roadworthiness of the car

[–]HellaBrainCells [score hidden] 13 minutes ago
Also watch out for cheap fucks over inflating the tires to make the vehicle seem more receptive

[–]baggybagel [score hidden] 13 minutes ago*
Where the hell are you people buying used cars?? Edit: I mean if you're buying from a dealer, not private sales.

[–]gimmebackmyracecar [score hidden] 12 minutes ago
My brother used to work at a dealership where someone traded a Porsche Boxster where they had actually covered the light with a piece of electrical tape, behind the cluster face so it was impossible to tell unless you took it apart. It was actually fuuucked.

[–]AgentKuma [score hidden] 11 minutes ago
If the car costs more than like a thousand dollars you should just skip all this amateur stuff and bring the car to a mechanic that offers pre-sale inspections, preferably a brand or type specific mechanic. They'll know exactly where common failure points are and how to quickly verify the condition of a car. They'll even tell you a fair price in your location. It only costs like $200 and it might save you thousands.

[–]pandafiestas [score hidden] 10 minutes ago
Just like how my air bag light has burned out in my car and now I don't have to ignore it!