Hello,
I have a standard European Mazda3 2004 1.6 litres where there seems to be something wrong with the engine control unit or PCM as it is called in the documentation. I have bought a used one on ebay and I am wondering if it will work to put the used ECU in my car and let the workshop program it to work with my old keys (PS: I only got the used PCM without any matching keys. So this means that i have two original keys that match the IC and Immobilizer unit, but not the used PCM i am going to put in).

I talked to a workshop mechanic and he stated that the ECU had to be reset before it was removed from the previous car or else he could not program it to work with my old keys. I am not sure what he meant exactly, but i found the following statement from the immobilizer documentation:

Replace PCM with Used PCM:
Using WDS: Security Access > "Ignition Key Code Erase". Two keys have to be registered to start the engine.

So the questions is: Must this ( "Ignition Key Code Erase" ) be done before the unit is removed from the old car or should I expect the workshop to be able to reprogram my new used ECU/PCM regardless of the state it is in as long as it works?

Best regards Eirik from Norway .

 

All he needs to do is follow the instructions on the M-MDS & transfer the data from your PCM to the replacement PCM.