Edmunds Answers


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  • avatar kiawah 12/31/07 12:09 pm PST

    Many chain auto parts stores (Pep Boys, Autozone, etc) will do a free reading of your error codes for you. The price on OBD2 readers have come way down, and the simple ones are very reasonably priced.


  • madmanmoo 12/31/07 12:06 pm PST

    Most common error reason for this is not putting your gas cap on securely. Can you believe it? It's true!

    Make sure that's secure first, if that doesn't work, then take the vehicle into your service shop and see what they think.

    Good luck!

  • kiawah 12/31/07 12:09 pm PST

    Many chain auto parts stores (Pep Boys, Autozone, etc) will do a free reading of your error codes for you. The price on OBD2 readers have come way down, and the simple ones are very reasonably priced.

  • mackabee 01/03/08 1:33 pm PST

    That's the oxygen sensor making the check engine light come on. Make sure every time you fill up that the gas cap clicks a couple of times when you tighten it. Most of the time this will go away. If it doesn't take it to your local Toyota dealer and have it checked out and reset.

    Source: I sell them

  • bepperb 01/07/08 11:47 am PST

    First tighten the gas cap a few clicks. It will take five or ten restarts before the lights clear if this is the problem. If that isn't the case, it may be bad gas, so fill your tank from somewhere else and let it run through.

    As was also posted earlier, most auto parts stores will read the code for free. It may be a bad O2 sensor, which you can replace yourself if you have decent tools or can rent them from the auto parts store.

  • sbonjonesy 01/27/08 8:27 pm PST

    Check your gas cap lots of Honda's and Toyota's exhibit this if you recently filled up and forgot to put gas cap back on. If it is the case simply retighten the gas cap and the check engine light should go away after driving for awhile.

  • mil6264 02/12/08 8:51 pm PST

    for that you will need to go to a garage that has a computer they will plug it into your vehicle's computer and the computer will tell what's wrong, most likely it will be an oxigen sensor, that is located in the exaust just after the engine

  • actualsize 02/28/08 6:39 pm PST

    I agree with most of the above comments. Most.

    There is no one reason why a check engine light comes on. It COULD be an oxygen sensor. It MIGHT be a loose cas cap (or one with a damaged o-ring seal.) It might be a dozen other things.

    Check the gas cap (and its seal) first. If that was it, the code will clear itself after driving continuosly for awhile. If it isn't the cap, have the codes checked at a dealer or auto parts store. Buying your own code-checking tool is OK, but sometimes one fault will trigger multiple codes. You don't get information about why something failed. Then what? Unless you're a competent DIYer, I'd take it to a trusted mechanic or dealer.

  • joel0622 03/20/08 9:05 am PST

    It can also occur if you leave the car running while putting gas in it. It will cause the car to suck in air and foul the Mass Air Flow Sensor.

  • rearwheeldrive 06/06/08 6:02 pm PST

    Oh yea it will go out after 50 start cycles or so depending on the model car, if the problem dosnt exist anymore. I erase codes immediately by removing the ground cable on the battery for a couple minutes. If their is a problem the light will reset itself.

    Which could be no problem at all. The red light means stop engine immediately, the yellow one says go to the dealer and get the run around.

    Service lights are just that, get service. Going to the autoparts stores above should tell you what needs serviced ,EGR Valve, MassAirFlow Sensor, Exhaust Sensor, If any one of these gets a bad signal the code is set off with nothing wrong with the part itself. Something like a sudden surge could throw off the normal signals these sensor pick-up tripping a code. Engine running more hot durring summer weather increased load on an engine in the summer or winter.

    They should know their codes Theirs usually 10--15 codes for basic sensor on the engine.

  • epgolfs 08/05/08 10:58 am PST

    Fully agree that the *likely* cause is the gas cap, however: Reseating the gas cap will NOT clear the code. Virtually any garage with a diagnostic machine can clear the code for you. It's a 2 minute job.

    My recommendation? Wait until you need an oil change & take it to a Toyota dealer. Tell them about the code & get it all done at once.

    1 stone = 2 birds.

  • waggawee 08/08/08 12:29 am PST

    Hi, let me help out abit seeing you have this long going problem with your camery. In the engine compartment you'll see a little black box looking like a fuse box, that is the dignostic connector. That box read the computer signal, or codes. I need you to find E1 and Te1 and use a piece of wire and bridge it. Then go into the car and turn full ignition on and watch for the check engine light to flash. Slow flashes are 10 and the fast ones are 1 ok. Meaning it make 2 slow flash and 4 fast flash then it would be code 24. and when you do so you just post the code and i'll tell you what is wrong with the vechile, as well as taking the battery cable off for 5 mins will reset yout computer and erase the codes, If a code comes back then a sensor is breaking down. (waggawee)

    Source: Auto Electrican

  • fatmando 08/30/08 6:20 pm PST

    a loose gas cap or a bad O2 sensor are the two most common reasons a car runs like new and have a check engine light on.

  • mario20 09/05/08 1:07 pm PST

    i had this problem and it ended up being that i didnt put the gas cap on all the way the light can take up to 100 miles to turn off after this

  • mrrealtor 10/03/08 11:49 pm PST

    I have a 1996 that runs perfectly and had a light on when i bought it. I did replace a sensor for around $100 but I stopped using gas with ethanol in it and my light went away and has not come back since I have been using real gas.

  • jerryq 11/07/08 10:43 am PST

    i go to auto zone "a lot" and the guys there say that a check eng. light on newer models can be something as simple as a loose gas cap. If you have an auto zone near you, they will check the code in your cars computer that is activating the lightfor free.

  • jkugler 01/27/09 9:18 pm PST

    I would say most likely o2 sensor, but if it's a false code, disconnect the battery for 10 minutes, hook back up, drive it for awhile, if the check engine light comes back on check your codes. Good Luck!

  • julesp 02/19/09 3:58 am PST

    Resetting the check engine light should not be taken lightly! 1996 EPA mandations required every car in the United States to be equipped with an OBDII (On Board Diagnostics/ 2nd generation) automobile computer that uses a universal diagnostic port with universal code meaning referenced with universal numerical code definitions. With these codes come access to real-time engine, transmisssion, abs, air bag,and body control function data streamed through a 16 pin diagnostic interface port placed under your dashboard and I/M readiness monitors (Inspection & Maintenance Information), and freeze frame data are kept in your on-board computers! The point being made here is once a check engine light is reset, the computer loses a LOT of information the EPA is going to look for when you take your vehicle in for an emissions test and unless you fully understand how OBDII works... using a simple code reader to turn your check engine light out will cost you more money in a short period of time unless you have the equipment, time, and ability to retrieve and reset this very vital information for the vehicle to pass EPA inspection and the test will reject your vehicle if the information they are looking for isn't present! If it is just a gas cap, tighten it down or replace it and drive until the light goes out. Your chances are better this way if you have an inspection soon. The newer the car the more strict the tolerance. 1996-1999, you are allowed two I/M readiness monitors not run 2000 & newer... only one!!! Seek someone familiar in this field for the monitors are hard to recover when they are reset!! Ask someone about drive cycles for your vehicle & see how many responses you get! I tried to condense as much info as I could in this summary and I hope this helps and enlightens you. Good fortune.

    Source: Julesp

  • Lobo 02/19/09 9:02 am PST

    You guys are right about those dad gummed gas caps. Bought a car 60 miles from home and drove all the way back a couple of days later. And about those lights, they come on at the drop of a hat. And if you have my luck, there wont be anybody that can understand the code it gives anyway. Hope that helps.

  • gizmo30646 07/07/09 9:20 pm PST

    lots of responses to this question. FIrst PLEASE! DO NOT DISCONNECT THE BATTERY WHILE THE ENGINE IS RUNNING. in later model cars this can damage computers. The gas cap code actually is caused by the evap system. it indicates there may be a leak in the tank. tighten the cap, if that doesn't fix it , replace the cap ( they do go bad ) if that fails , a dealer can do a smoke test to determine cause of code. ( some independent shops have brought the equipment to do this test with but they are few and far between) but don't guess, get the codes read at local parts store and follow their advice. codes are a gray area, just because you get an O2 code doesn't mean you have a bad O2 sensor. it takes training , skill and experience to know what to do with those codes. example engine runs way rich , horrible idle - O2 codes set--caused by the engine coolant temp sensor.- bad sensor told computer it was 40 degrees out side--it was 90- -
    car was running for cold weather. reading data flow it just as important as reading codes.

  • automd1 07/14/09 8:28 am PST


    Their was a recall several years back on their gas caps , their gas tanks are presurized systems What you are describing is what was happening If a gas attendent does not put your gas cap on properly that can cause it as well. Make sure that when the cap is put on to here the safty clicks.

    Take the gas cap off look to see if you see visual damage if not, reienstall. Disconnect your positive battery cable for about 2 minutes, this should reset the computor. everytime you get gas watch the gas attendant. You may have to replace the gas cap even if it looks ok.

    let me know how you make out


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