Wife's 2003 Toyota Corolla - computer update?

Discussion in 'General Tech - Auto and Truck' started by mattw, Apr 1, 2010.

  1. mattw


    Okay, so my wife's '03 Corolla has about 103k miles on it and since about 80k has been intermittently throwing Code P0420: Catalyst system efficiency below threshold (Bank #1).

    I know that it means there are four possible causes: leak in the exhaust system, faulty sensor before the cat, faulty sensor after the cat, or the cat has failed.

    We had the light reset after it came on at 80k and it was good for ~10k miles. Then it came on again. Then it went off again. Then it came on and has stayed on for about the past 6k miles.

    Before trying to fix it, I googled the code and found reference to a Toyota TSB #02804 referencing this code that seems to say a computer update is needed.

    I called the local dealers hoping someone would say "Yeah, since that TSB went out - go ahead and bring it in we will update the computer free of charge and see if that fixes it." What I actually got, even after describing it as intermittent and mentioning the TSB, was "Your Catalytic Convertor is probably bad, you are probably looking at a $2k repair. Bring it in and it will be $100, we will run the codes and work up an estimate for you - but I'm warning you it will likely be $2k."

    If we didn't need it to pass emissions I would just keep driving it. Add to that the fact we have been thinking about selling this car for about a year now.

    Questions: can independent mechanics update the software like that TSB seems to say should be done? Are there any magic words I can say to the dealer to force them to just do this update so I can do the work myself?

    Thanks for any help guys.
  2. lingo


    atlanta, ga
    Unfortunately you are stuck with the dealer reflashing the ECU. Have you tried a different dealership? Some times you can find someone more helpful if you "shop" dealerships, just like when you bought the car? Maybe you could just go to the dealership and just walk into the service department and talk to one of the service advisers and ask them about the update. I have found that many of them are more helpful when you are standing in front of them. Good luck.

    You know that you can have an independent shop take a look at the car. They can take heat readings off of the cat and tell if it is blocked or if one of the sensors is bad. They don't have to do the work. It will probably be cheaper than $100.
  3. wxm

    wxm SILVER Star

    +1 on getting a second opinion. It could be something like O2 sensors...
  4. mattw


    Talked to two dealers and toyota customer care - the customer care lady said that if this code is being thrown the repair manual says that they are supposed to reflash the computer and replace the catalytic converter.

    When I talked to customer care they said that we had to take it to a dealer to get an official diagnosis. We did. Dealer said "We need to replace the cat." Armed with what we knew from the customer care folks about what the repair manual said, we asked them to reflash the computer FIRST and then see if there is still a catalytic converter problem. After sticking to my guns through a few phone calls we got them to reflash the ECU.

    So far (about 80 miles driven) the light still hasn't come back on. Hopefully this will get us through emissions so we can have time to figure out what the actual problem is.

    Going to find an independent mechanic to find out what the real problem is - I really hate dealership mechanics.

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