Exchanging ECM's

[ic_ou812]

I have a 2003 Corolla S, 5MT with the dreaded P0420 error code that I can't get rid of. The dealer tells me the ECM in the car is either 89666-02133 or 89661-02080 by the VIN.

Since I don't want to risk the dealer bricking it by reflashing and being out the cost for the flash and a new ECM. I want to know if one from an 05 or 06 5MT will work with out flashing to get the higher rev level firmware.

Is it worth looking at any 2004 ECM's since the TSB EG028-04 includes 04 models?

I found that the 2005 5MT had the following ECM's: 89661-0Z041, 89661-0Z042, 89661-0Z043, 89661-02D11, 89661-02D12

I found that the 2006 5MT had the following ECM's: 89661-02D01, 89661-02D02, 89661-0K20, 89661-02C13

Does anyone know what the difference between them is? Are they interchangeable since neither years came with an immobilizer? The dealer told me the immobilizer came on the 07 model.

I am trying to avoid paying for a new cat if the problem is the tolerances on the 2 sensors around the cat. I have found TSB EG028-04 that advises a reflash but indicates that a certain ECM may be bricked by the process. I have read that the earlier ECM's had a tighter tolerance between the 2 sensors and the latter ones were looser eliminating the CEL that I need to get off to be emission tested.

thanks from a new member/lurker here...

[dorman68]

I am called my local dealer out of curiosity, here's what the parts guy stated. All 05 and up Corollas have the immobilizer as a standard option therefore an 05 or later won't work in an 04 or earlier corolla as all 04 and earlier Corollas did not have an engine immobilizer.

[hardtopte72]

You can see the number yourself. Go under you glove box and pry down the plastic door held on by 2 plastic clips under the glove box. Grab your flashlight and you should be able to see the ecu part number.

[MasterTecInSTL]

There is almost no risk to bricking a PCM from flashing if the proper procedures are followed. The only single time I saw it happen was a car that had a custom program already flashed and it bricked when we reflashed it with the stock programming. The customer was well aware of the risk before we started.

If you have one of the non-programmable PCMs then it will simply fail to program - not be bricked. Besides it is the dealer's responsibility to double check the part number before performing that PCM so even if they did brick it I would think it would be their responsibility to take care of things.