Replacing ECU-anything tricky? - Toyota Nation Forum : Toyota Car and Truck Forums

holler1 · 05-25-2009, 07:29 AM

Recurrent P0420 code on my daughter's 03 Corolla. Replaced O2 sensors and MAF in January. Checked O2 sensor signals and they indicate Cat is OK, also no smell from exhaust. A TSB indicates the ECU itself may be the problem. I don't have access to the car but will visit next month and check it again. I'm thinking about replacing the ECU with a used one from Ebay ($125) to see if that fixes the problem. Is there anything to replacing the ECU other than just unplugging the old one and plugging the new one in? Has anyone else done this? Is there a better source for a good (but cheap) ECU?

ems · 05-25-2009, 02:24 PM

Don't buy a used ECU. I bought one for my corolla and I found out that we have to have the dealer put in the vin # of the car into the new ECU. They advised me that this could only be done once and that I would not be able to use the used ECU. I did just try to put it in anyway and it would not work.

holler1 · 05-25-2009, 06:10 PM

Thanks for the warning. I wondered if there was a catch.

dorman68 · 05-25-2009, 07:39 PM

Quote:

Originally Posted by ems

Don't buy a used ECU. I bought one for my corolla and I found out that we have to have the dealer put in the vin # of the car into the new ECU. They advised me that this could only be done once and that I would not be able to use the used ECU. I did just try to put it in anyway and it would not work.

Encountered the same problem on my buddy's car. Had to go to the dealer and get a brand new ecu flashed(programmed)