Bad ECM?

[doctorh]

Hi, I've been doing quite a bit of reading on this forum and finally decided to sign up to ask a question. I have a 99 Corolla with 70,000 miles. Check engine EVAP codes keep popping up (typically 0420 and 0446 I think). My mechanic replaced the canister, some hoses, and I got a new gas cap. Didn't help anything ... after resetting the codes, usually they come back within a day. I then proceeded to take the car to my Toyota dealership who looked at it and said everything was fine and I need a new ECM. Should I be suspicious, given that it seems the ECM is the most expensive part (they want to charge me $2000)? My mechanic said this is a waste of money since nothing seems wrong and spending $2000 on an ECM may not even work to turn the light off.

This was all over a year ago - I have been driving the car with my scanner attached and I just clear the codes whenever they come on which is basically once every day or two. The car is great and drives fine with no problems. The car even passed emissions (I cleared the code before going) so maybe Toyota is right and the codes are firing incorrectly. The only issue is that I am thinking of selling it in the next year or so and am worried no one will buy it because of the stupid check engine light! Does anyone have suggestions on how I might fix this without needlessly spending lots of money? I don't know how many more $100 "diagnostic" fees I can take.

[gaj1967]

You can get a re-manufactured one for under $125 ($371 for California emissions) from Rockauto.com

The ECM's hardly go bad. Could be bad O2 sensor.

Info on P0420: http://www.obd-codes.com/p0420
Info on P0446: http://www.obd-codes.com/p0446

Gil

[TenZen]

ahh 420...i hate that code.....changed that sensor twice and it still comes up.

[Bingo]

Why bother ? I just had this issue and I am not going to spend time and money on my 99. As long as it passes Smog who cares ? If the light bothers you figure out how to pull the bulb. Dingo

[fishexpo101]

Should have the EVAP system "smoke" tested. Basically they fill the whole works with a tracer smoke, than use a probe to sniff out areas that the smoke is pouring out as they cycle the EVAP system. The evap codes have always been a PITA problem with the 8th gen Corollas.

Also, don't be tempted to top off the tank - on 8th gen Corollas, they are very susceptible to being easily overfilled. All that gasoline will eventually makes it way to the vapor canister and cause lots of headaches for you.

Smog laws vary from area to area - some places, you will automatically fail with any CEL. Some reset the ECM prior to being smogged, but in area that do an I/M or I/M 240 check - that will also automatically fail the test. Some areas will allow you to run the car on a chassis dynometer while monitoring emissions via a tailpipe sniffer instead, but not all areas will dothat.