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2004 Toyota Camry code issues & fixes

Home Forums Stay Dirty Lounge Service and Repair Questions Answered Here 2004 Toyota Camry code issues & fixes

This topic contains 3 replies, has 2 voices, and was last updated by Nightflyr * Richard Kirshy 9 months, 2 weeks ago.

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  • #899711
    Diane Morris
    Diane Morris
    Participant

    About a month ago I ran diagnostics from my Fixd app/device which gave me a 0420 code. From this, I replaced my downstream o2 sensor. Things seemed fine again and the check engine light was off. A couple days ago out of nowhere, my car suddenly ran super rough and had no power at all. The check engine light was not only on but FLASHING! I ran diagnostics again to show 0303 code. Ended up the ignition coil for cylinder #3 was bad. Replaced that along with all 4 spark plugs. Again it ran fine on the first time driving it but when I took a short trip later in the day, it was back to the check engine light being on with a 0420 code once again. Could this be happening due to yet another problem not yet addressed or possibly due to something not being done correctly in either of the first two fixes?

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  • #899854
    Nightflyr *
    Richard Kirshy
    Participant

    Possible causes of P0420:
    Faulty oxygen sensor
    Faulty air-fuel sensor
    Worn or internally failing catalytic converter (Most Common)
    A leak in the exhaust system
    Misfire (the root cause of converter failure)
    Rich or Lean air-fuel ratio (the root cause of converter failure)

    Many times this code is thought to be a faulty O2 sensor or A/F Sensor; while a possibility, the most common problem is a faulty catalytic converter. Do not overlook other codes that are paired along with P0420. Codes like P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, and P0308 are misfire codes, and these codes require misfire diagnosis. If the catalytic converter is replaced without repairing the misfire, the new catalytic converter will go bad again. Also, make sure you don’t have codes P0174, P0171, P0172, or P0175 which can mean the engine is running rich or lean, which can burn out your catalytic converter. If these codes or any other codes are present, they should be addressed first.

    #899873
    Diane Morris
    Diane Morris
    Participant

    I originally had the P0420 code which, when checked, proved to be a faulty downstream O2 sensor. So that was replaced. The code was cleared from the system before the problem arose with the P0303. I took the ignition coil from the 3rd cylinder and swapped it with the one on the 4th cylinder, ran diagnostics again and it changed the code to P0304 thus telling me it was a bad ignition coil. That was replaced and just for the sake of doing it I also replaced the spark plugs. The system was cleared of all codes again when it came back up again with the P0420. No other codes show in the system currently or were paired with the ones that came up previously.

    #899985
    Nightflyr *
    Richard Kirshy
    Participant

    I would suggest looking at both long and short term fuel trims to see if there is any issue with running rich or lean.
    From there I would check the cat for proper operation.

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