I have an '04 AT RX-8 with 6k miles and this morning the engine light came on and didn't go off. I promptly took in to the dealer and waiting an hour while they put it on the computer and here is the response:

The computer codes were incomplete because we don't have the proper diagnostic software. Mazda is downloading the software to us, but it will take awhile since we don't have DSL.

They put me in a rental and will call me later. The mechanic thinks the PCM may need to be changed.

Very weird.

 

I can believe the statement that their WDS is not up to date. Apparently, the software is updated fairly regularly. So they are probably being strait with you as far as that goes. I think the mechanic is making some assumptions--correct or not--since he apparently has not been able to query the PDM, although he could have pulled the error code with a simple CAN scanner.

Be patient and I'm sure they will get to the bottom of it. CEL's can be caused by any number of "problems" including the simple "gas cap not tight syndrome".

 

Well Mazda just called me and they are replacing the PCM. I have to go drop off my keys now so they can be reprogrammed and I should have my car back tomorrow. How can a whole PCM go bad? or is replacing simpler than diagnosing the actual problem? Obviously I am no expert on these things.

 

Well, the PCM is a computer with solid-state components, and it gets real hot under the hood of this car. So, it's not TOO surprising that a component might fail. There have been posts from other owners reporting on PCM replacements. (Do a search if you're interested.)

The answer to your last question is not necessarily. Apparently there was some indication of a PCM failure, otherwise they will still have to deal with the original cause of the CEL. Time will tell, 'cause if there is a problem with some other component in the car, you will probably get another, similar CEL down the road in the future.

 

After 2 days, I got my 8 back from the dealer with a new PCM. Here is the text of the ticket:

Customer states check engine light stays on all the time. Inspect and report. P0607 Code setting the check engine light. Pulled codes and called tec line ref#403267 spoke to Jeff and was told that the PCM as built data corrupted and the PCM had to be replaced with fresh as built data. Obtained the as built data from tec line and followed the procedure for installing a new PCM and entering the as built data then reprogrammed all 3 keys customer supplied and test drove to verify repair. All OK at this time.

Bottom line: PCM crashed, new PCM installed. Everything seems fine now. I don't know what flash was loaded though.