What to do when Your Vehicle Check Engine Light Turns On and the Warranty has Expired

I wish to share this simple piece of information that has saved me thousands of dollars over the past several years.

Yesterday my vehicle check engine light turned on and I knew what to do.

I have never owned a new car; I always buy used. I usually buy an American model lease back or rental return with around 25,000 miles on it which saves me $10,000 – $20,000 on each vehicle purchase, and that allows me to stay out of debt (which my wife and I abhor). The risk is that the factory warranty expires 5,000 – 10,000 miles after purchase, so I could end up with a useless car less than a year after purchase, but that hasn’t happened.

What has happened is the check engine light frequently lights after the vehicle exceeds 50,000 miles. In the past when this happened, I always took the vehicle to a dealership to have them diagnose and fix the problem. I’d have to make inconvenient commuting arrangements since I’d loose the car for 1-2 days, and a repair was required that cost between $500-$2000 dollars. Since I am a mechanical know-nothing, I accepted the dealer’s word, made the repair, and paid the bill. I don’t recall how many times I’ve been through this repetitive cycle, but it’s been often enough to cause me a lot of frustration.

I don’t remember where I learned this, but several years ago, I learned that I didn’t need to go to a dealership or another garage to find out why the check engine light was lit. I didn’t even need to buy any special equipment to find out why it was lit.

Today I take the car to an auto parts store like Auto Zone or Advance Auto Parts and tell the guy at the counter that my check engine light is on. He plugs a handheld electronic device into my car, and tells me why it is lit. Several times, it said “emissions problem” – translated – A LOOSE GAS CAP! We tightened the gas cap, reset the light, and it didn’t light again for months. Other times it was a plug misfire, which can be a complete aberration. Again, we reset the light and it didn’t light again for months. A couple times, repairs were required, but at least I walked into the dealership with knowledge, which helped me keep the cost down. With knowledge of the problem, they couldn’t B.S. me.

The best part – it’s something you can do in five minutes that may save you thousands of dollars.

You can also buy yourself your own inexpensive Diagnositc Code Reader.

Check out Amazon’s entire assortment of ODBII Diagnotic Scanners.

To some readers this may be common knowledge, but for those of us that are mechanically challenged, it will save you cash.

170 thoughts on “What to do when Your Vehicle Check Engine Light Turns On and the Warranty has Expired”


  2. Today morning, i woke up with the CEL nightmare! (and my first encounter with this irritating ‘What if’)
    I read all the comments on this site and quite a few others including inputs from the Haynes Manual for the Corolla 2000.
    This is what I did and it worked to get rid of the Check Engine Light(with my peace of mind intact):
    a) Got the error code after the free diagnosis at Autozone(friendly guys at rockaway, NJ). Found that it was: P0171 i.e Fuel injection system lean, in layman’s terms or getting it down to absolute dummy terms for folks like me -> Clean the Mass Air Flow Sensor in most cases.(you could google for this sensor to learn abt what power this lil thing wields!)
    b) Bought the best recommended sensor cleaner for this class -> CRC Mass Airflow Sensor Cleaner, a product from CRC industries. You can get this for 7 $ from Pepboys
    c) Locate the sensor in the car. Disconnect the sensor’s electricals, remove the 2 screws(a normal star crewdriver is good enuf) and release the sensor from the air filter housing
    d) Spray the cleaner 10-15 times on all sides, especially on the hot-wire sensing element and the other connectors. Once its cleaned, reinstall the sensor back once its dried(the fluid evaporates pretty fast)
    e) Start the engine and drive around for some time. You’ll already find an improved response from the engine.
    f) Reset the code information from the computer memory by removing the negative cable of the battery.
    In my case, the CEL vanished as i was driving the car after re-installing the filter. My friend who did the same thing for his Jetta got the CEL cleared after removing the negative cable in the battery.
    Wear Gloves, Be Safe and best of Luck!

  3. It is never easy to understand what might be causing the check engine light to come on. The only thing that you can say for sure until the vehicle is diagnosed with a scan tool or code reader is that the OBD2 system has detected a fault that may cause the vehicle’s emissions to increase.

    For more technical information on this subject, see the following pages:




  4. I own a Toyota Camry 2000. Bought it used in September 2006. No problems so far, except Check Engine Light came on yesterday. Wondering if it could be engine oil or something else. Plan to hit Auto Zone tomorrow as many here have suggested but just wondered if anyone has any input before I do that. Thanks!

  5. Considering that I have not received any response in the last 24 hours, it seems nobody really cares about this topic any more, but I will still go ahead and say that after I added two quarts of oil the Check Engine Light went away. It took 24 hours for the light to go off.

    Here’s an interesting thing I found out about the engine oil dip-stick. It is a short stick with a yellow handle that is almost hidden below the engine, not the long, unmarked one in front, that looks like it is the engine oil dipstick.


  7. Patrick,

    To be perfectly honest, I am not 100% sure but I believe it my Camry is 4-cylinder. My 2 main reasons for this belief: (1). I get 25 mpg in the city. (2) My car does not accelerate as smoothly or as quckly as 6-cyl. cars usually do.

  8. Briefly, this is my experience with the ‘check engine light’ on my Miata. I had just purchased a ’94 Miata and added a car bra to cover the blemished fiberglass front end. A short while thereafter the dreaded ‘check engine ‘ indicator came on. I took it to my mechanic and he told me that it was a code 17 = ‘heated oxygen censor’. As soon as I removed the Car Bra the code 17 was removed.

  9. “To be perfectly honest, I am not 100% sure but I believe it my Camry is 4-cylinder.”

    You can’t tell whether it’s a four or six cylinder just by looking at the damn thing???

  10. I suppose I could tell if I ever bothered to look at the damn thing. However, pretty much anything that is under the hood or between the wheels is something I choose not to mess with at all. I keep my car clean, inside and out and I look at the lights on the dashboard — and that’s it.

  11. Dear Anpadh,
    All you need to do to find out whether your ride is V4 or V6, pop the hood and count how many wires are on your engine. If you see 4, then is 4 cylinder, if its 6, its 5 cylinder.

  12. Jay,

    Thanks for the tip. I will try to do that when I pop the hood to re-fill the wiper fluid. One tip I would like to pass on, from a mechanic, is that if the check engine light starts blinking, stop immediatey and take it to a mechanic. But if it is steady, and you know that you have sufficient engine oil and other fluids, all taken care of, you can afford to ignore the light until you are ready to take the car for service, in a month or two. My check engine light has been going on and off the last two months. I’ve taken it to more than one mechanic and they all say to ignore it, as everything seems OK.

  13. 2001 SAAb P3 CE lite comes on. Diagnosis reads PO0300. Been to Saav mechanic three times. Twice replaced the ignition coil set $264 + labor(all four in a unit). After 20-30 miles CE light returns. Went back today, mech reset CE. Drove off, stopped for lunch, CE light returns. This is driving me up the wall. If there is a random misfire how can it be located?

  14. Brenda,

    The same thing used to happen to my car. What happened in my case was that the water pump was broken and the timing belt was frayed. It cost me about $500 to get those problems fixed (parts and labor included). Now, the Check Engine Light does not come and go. Your car may have a different problem. I suggest that you go to some place like Pep Boys and have the car properly analyzed. I believe Pep Boys does the analysis for free.

  15. well, after reading all of these and knowing I have a PO440 code reading on my ses light (yep, free from Autozone) and worrying about how much this will cost me to fix since my warranty is up (2003 TB), I’m going to bite the bullet and take my baby to the doc (but NOT a dealer). I will gladly pay the $80-100 for a full diagnostic and hope for the best. I’ve replaced the gas cap, air filter and fuel filter because they needed it. Now I’m hoping it’s a sensor and not the thingy in the gas tank that causes leaks that maybe a recall but I’m not holding my breath. yep, time to stop being a diehard “buy American” but I sure hate jap cars style. they have slanted tail lights . . .

  16. Thanks for sharing this experience. After freaking out a little when the check engine light went on in our barely driven truck, I sent my Hubby to Schucks to get it hooked up to their testing kit. They did it gladly and determined that it was a leaky gas cap. Which gave him the perfect excuse to replace with a locking gas cap, even though their prices have gone up due to high gas prices. But it saved us so much in comparison to taking it to a dealer, time AND money.

  17. My hyundai sonata (64K miles) CEL was on due to Gas cap not being tight enough (TIght upto Three click sound). Surprisingly after filling up for 100 of times, this mistake can happen and CEL can light up. Amazing!

    Thanks to AUTOZONE who detected it for FREE.

  18. I have a 2001 Nissan XTerra and the check engine light comes on periodically. It has never been anything other than the gas cap being put on too loosely. It had not happened in a while, so today I forgot and took the car to a repair shop. They tried to sell me a “knock sensor”for $700 (parts and labor). That was enough to jog my memory about the whole gas cap thing. So, I told them to give me an oil change and a new gas cap. I will fill it up with gas again and see if the light comes off with the new gas cap screwed on tightly.

    Is there any real danger to driving around for a few days with a faulty “knock sensor,” in case this is not a scam??

  19. Check engine light 96 Grand Jeep Cherokee and when I did when another person had same car/same problem…the cruise light came on, but NO code numbers.

    I don’t use Cruise Control…should I worry?


  20. I recently had the check engine light come on in my 2003 Toyota Tundra. After researching online, I went to Autozone. They said California does not allow them to scan for codes, but I could do it myself using their equipment if I put down a fully refundable deposit. I did this, used the scanner myself (which was very easy) and found a code #. The Autozone folks looked up the code and printed out a list of possible causes (leaking gas cap was one). While deciding what to do, I filled the gas tank and lo and behold, the light went out. Apparently, I had previously let the gas tank get too empty which triggered the check engine light. I had read about this happening to others. Cost of solving the problem–one tank of gas. Hope this helps someone else.

  21. I have a 96 Nissan Altima that refuses to pass all of the readiness tests. There is no check engine light, it just won’t get ready. The ones that won’t get ready are: 02 sensor, Catalyst, and EGR system. To pass emissions, all of the codes but two must be ready, and since I have three not readies, it won’t pass. We’ve driven it well over 100 miles over several days, and still won’t get ready. On my Saturn I had this same problem and it turned out to be a bad coolant temperature sensor. But I’m at a loss on this Altima. Any suggestions?

  22. I changed the battery in my ’01 Lexus RX300 this morning and filled up the tank with gas this afternoon. About 4pm, I went out to run an errand and noticed the Check Engine and VSC lights were on. After googling check engine light and reading what all of you have written above, I disconnected the battery and made sure the gas cap was tight. For good measure, I checked to see if any vacuum hoses near the battery had been disconnected in my zeal to get the old battery out and the new one in. When I reconnected the battery, the lights were reset and have not come on again. Pretty sure it’s “fixed”, but I’ll keep my eyes on the idiot lights for the next few days. Thank all of you who have shared your knowledge here.

  23. Hi,

    Thank you very much for your suggestion. It really worked for me and saved my money..

    Thanks again!!!

  24. Ok thatis great information. But part of our problem is how do you resetr the engine loght. I have a 2002 sl1 saturn. And I don’t know where to find it’s reset. If you have any idea I would appreciate it thanks.

  25. I kept getting different things fixed on my car and the light kept goign off and then returning a few weeks later. Last month, a mechanic who checked out my car thoroughly told me that the light was over-sensitive. Apparently, one of the reasons it comes on has nothing to do with the engine but with the government’s anti-emission laws. If the EGR valve is even slightly off, the light comes on and stays on forever. Usually, the EGR valve itself is fine but the VSV (Vacuum Seal Valve) needs replacement. For my 2000 Camry, that means about $120 ($75 for the valve itself and the rest for labor, taxes, etc). INterestingly, however, the EGR and VSV do not affect performance in any way. And the EGR tends to last 12 to 15 years. Most mechanics tell you to replace the EGR and then, a couple of months later will tell you to replace the VSV too. Thte total cost comes to (for me) about $500 and all of it is 100% unnecessary.

  26. This is a great site and I have learned some very helpful hints and insights, especially about having the CEL code checked out at the auto parts store and to ask upfront how much it would cost. I too, have a story about CE lights to tell:

    I have a 2002 Corolla. In August 2007, the yellow CEL came on the night before I had to drive back to San Diego from Oakland, CA. It was drizzling. I took the car to a mechanic as I did not want to be stranded on the freeway. Mechanic said it was the catalytic converter, but couldn’t get the parts until Monday (two days later). He assured me that it was safe to drive back to SD and cleared the code. I paid him $35. Drove back to SD without incident. In October, I finally took the car to have the catalytic converter replaced.

    The mechanic asked me why I thought I needed to have the catalytic converter replaced. I told him what happened. He asked me what the code was which I did not have. After learning the car only had about 90,000 miles, this mechanic said it couldn’t not be the catalytic converter. He hooked the car up to the analyzer but no code came up. He told me to bring the car back if the CEL comes on again. I didn’t have to pay him anything, which was was grateful.

    In November, I took the car to the dealer for a 90,000 mile maintenance. The car was fine. Paid $350 for routine maintenance stuff. They hooked the car up to the analyzer too, and again, no code came up. Two weeks ago, the solid yellow CEL came on again, in Oakland. It was also drizzling. I added one quart of motor oil and have been driving the car with the CEL on, but I worry that it may make matters worse by ignoring it.

    The dealer charges $90 and 1st mechanic charged me $35 just to check it out. Worse yet, I don’t want to pay hundreds of dollars to have the wrong part replaced. I would have been very upset if I had wrongly replaced the catalytic converter. After this experience, how do I know whatever the next mechanic told me is the right thing to do? After reading all the helpful posting on this site, I cleaned the gas cap, making sure it was straight and tight, filled the gas tank, but solid CEL is still on. I called Kragan, but they only sell the scanners. Here’s my plan:

    1. Will call Autozone and see if they can pull the code for me, or
    2. Borrow the scanner and do it myself (since I live in CA, they might not pull it), which I really don’t know how, but hopefully Autozone will offer some assistance.
    3. Read the owners manuals.
    4. Check all fluid levels and do a general inspection under the hood.

    Any other suggestions?

    Both times, the CEL came on in Oakland when it was cold and drizzling. Could rainy days and high humidity cause the light to come on?

  27. 2002 Corolla CE Light update.

    As planned, I took checked all the fluid levels, and inspected the hoses under the hood. Took the car to Autozone. Ws told that they are not allowed to retrieve the code in CA any more. But could loan the scanner and instruct me to do it myself. The code was P0420, readout says: Catalytic converter low efficiency thrushold. The car has only 95,000 mile on it and I was told that catalytic converters lasts at least 200,000. Now I just don’t know what to do any more.

    There is another related problem with the car. I hear high pitched squeaking sounds when the car starts up in the morning but goes away in 30 seconds or so. It is coming from the front left side of the car, may be the belts. Any other ideas?

  28. You may want to look at the website. Basically, it comes down to checking 5 things: The catalytic converter itself, the VSV (vacuum seal valve), charcoal canister, purge valve, and sensors.

  29. Thanks Anpadh.

    Autozone cleared the code for me and it did not come back on. So I’ll just wait and see. BTW. The Corolla owner’s manual does absoutely no help. It only says to take the car to the dealer.

  30. Well…this morning I have the dreaded CEL “ON” in my 2000 Dodge Durango. this is a car that has roared to life virtually without problem for its entire life. This morning, it wouldn’t start. Took 6 or 7 tries. Then, when it came roaring to life on the 8th try, the little light was on. It is raining like crazy here, and I’m wondering – (being a SoCal gal, where rain is rare and appreciated) – could water be the problem?

    This is a “I have no money right now” issue. Honestly, I’d be happy for my local NAPA dealer to check it ($88) if I didn’t have a sneaky suspicion that driving it in the 1″/hr rain home last night was perhaps the cause of my problem….and, of course, if I had the money handy….

  31. my 1996 mercedez SL320 check engine lights came on after I put gas in my tank. it is lit, but not blinking. I haven’t checked re-capping the gas tank. if that should work, i have isolated the problem. if not, then off to quality tune-up i go for code reading. any help is appreciated first before i go to the shop. thanks.

  32. I will answer my own question posted above. I recapped my gas tank- no dice. CEL light still on but not blinking. Took car to my body shop mechanic. Mechanic scanned car..printout is “P4011 Secondary outflow intake” message but car is OK to drive. With my mechanic’s help we were able to isolate air pump and visually checked hoses attached to it. Car is left overnight but hopefully it is minor (If i have to replace the air pump hose, cost is only 20 bucks; airpump itself including labor will cost me about 300 dollars.) Still a bargain IMO.

  33. Well, the CEL came back on one week after I had it cleared for free at Autozone. I have been driving with it on. May take another trip to Autozone soon. I amy consider changing the gas cap. But is a loose gas cap is a problem, why do I need to worry about it.

    I also came from So Cal. And the light only came on when I am in No. Cal. So may be the rain and the humidity did have something to so about it.

  34. I have a 2004 Volvo S60, and had a new catalytic converter put in about 3 weeks ago…the next week, it passed emissions. Then it started making noise again. This past weekend, the CHECK ENGINE light came on (came on Saturday night and stayed on all day Sunday…Monday, it was off again) so Monday, I took it back and the guy adjusted one of the brackets or something, which fixed the noise. Tuesday morning, the CHECK ENGINE light came back on. Car seems to be running fine. Last night I stopped at our neighborhood parts store (Advance) and the guy hooked it up to the computer, and said there was nothing wrong with it. But he said he wasn’t allowed to reset the light.

    I’m trying to trade the car in this weekend, but I need to get the light turned off! Help!! I’m going to try other auto parts places today…if that doesn’t work, I’ll call the guy who did the catalytic converter, but he’s about 20 miles out of my way…

    Any other advice?

  35. Hi beth,

    I’d see the mechanic who replaced the catalytic converter. The only people who are qualified to work on issues such as these are ASE certified mechanics. Don’t assume we know what precipitates the CEL lights on. These mechanics (the one I know anyway) will hook up their OBD scanner, scan the engine, and will reset the lights for free but if you allow them to do their job, including replacing the suspect parts, that would be your best insurance from keeping the CEL lights on.

    BTW, the mechanic I know was more than honest with me…he said automakers put these CEL sensors on the cars they make, not to cause internal problems within the engine but rather as an emission tool for when you need to smog check your car to comply with state DMV agencies. In other words, he said these are unnecessary expenses that we consumers unfortunately have to deal with. You want cleaner air to breathe, then indirectly we pay for it by virtue of when our CEL lights come on. Good luck.

  36. I have just bought a MAZDA 626 IT, American model, engine YGE22, 190 000 miles on the dashboard. The check engine light always goes on 5 minutes after I start it and goes off only when I stop the engine.

    I have read all your advices, but I cannot see what I should do in my own case.

    Any help ? Thanks.

  37. Abou — You may want to check your engine oil and other fluids. It could just be an electrical problem too. The light may be on despite there being nothing wrong with the car because bad wiring i activating the switch.

    David — My sympathies! On the other hand, at least you know what to fix. And, since it is an American car, fixing it should be relatively cheap.

  38. Thanks David and Anpadh for these very interesting contributions. I am unfortunately not a mechanic, but I will see this with an electrician as well. I will certainly be back to share with you the results of this trial.


  39. I just bought my 99 Saturn SL2 about a month ago….with the engine light on(dumb right)…well within 3weeks the engine was shot…i took it back to the lot and had to pay $1100 to have the engine replaced…2 days later the engine light was back on…

  40. My story is very similar to some mentioned here. Needed a smog check on my 2000 Honda Accord LX , check engine light has been on for months without any issues, procrastinated on it until I absolutely had to get it turned off for the smog check. I took it to a friend of mine who works at a car repair place. They charged me $20 to diagnose it but couldn’t figure out how to shut it off , just so i could pass my smog. Took it to the dealer where they wanted to charge me $100 just to see why it’s on. Came home all frustrated and did a few google searches and found THIS site.. I read some of the suggestions and figured I’d give some of your ideas a shot. Went out to my garage (first made sure I had my code to set the antitheft code back for the radio) and unhooked my car battery for 3 minutes, hooked it back up and to my amazement the light is now OFF. I can now get my car smogged without the inconvenience of paying hundreds of dollars to have the damn thing shut off. Did it myself and it took less than five minutes. Make sure you have the code for your radio before doing this. Thanks everyone for helping me.

  41. Disconnecting the battery can help with a stubborn check-engine-light, but the computer will note that it has been disconnected recently. You’ll need to drive around for ~100 miles to give the computer enough history to pass your smog check.

  42. Este es unaoteccion de los gobiernos para vender mas carros nuevos
    porque si tu ves esa lus no andas agusto y luego tratas de comprar un carro nuevo.

    ppero en realidad no pas nada si tienes engene lights on

    despreocupate o funele el foco y ya estuvo

  43. Disconnecting the ground cable of the car’s battery for a minute or two will usually clear the check engine light. Some cars have an automatic light turned on at certain maintenance intervals. These are triggered by the odometer reading and serve as a not so gentle reminder to have the car serviced.
    Make sure that you drive the car right away for about 15 minutes and at least once at highway speeds to see if the light comes back on. If it does then the car probably has a problem.

    Allot of National and Multi-State car parts retailers like Pep Boys, AutoZone, Etc. will read the codes on your car for free because they want to sell you the part to repair it with.

  44. I have a 1999 GrandAM Pontiac my car stalled in the middle of the road. Took it to a dealer, he replaced the ignition coil. But since the car has come back from Garage there has been 2 problems
    1) Chek Engine light is on
    2) Car does not start in the first try

    I took the car back to the garage (Auto Select) He says that starter of the car seems to be starting to turn bad and check engine light scan code was P0420 he reset it and said that it could be because of the earlier prblem and I should run the car for 400 to 500 miles before resetting the light again.

    Can someone please advice as to how my car suddenly has started giving starter problems since the time it has come from garage and has that anything to do with Check Engine light

  45. Most likely, you have one of three issues: (1) The spark plugs need to be replaced (2) The fuel injection is injecting too much or too little fuel, at starting. This could happen if the oxygen sensor is not working right. A bad oxy-sensor will also trigger the check-engine light. (3) Your alternator is dying (but not yet dead).

    It is also possible that your battery is dying but if your headlights, stereo, etc. are all working fine, then that is extremely unlikely.

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