Hi everyone, just joined here.

Anyway, my CEL came on about half an hour from the Mazda dealership after my engine blew and I had a new engine put in, under warranty, thank god..

Considering it was 9 PM and the light eventually went out I didn't take it back. The day after it came back on again when I went driving and it's been on since then. I had a code for a bad gas cap before the rebuild, which I figured it was, until I finally replaced the cap and it failed to go away.

Yesterday I took the car to AutoZone where they ran the codes and nothing came up.

So now I have a CEL on with no codes showing up and no idea why.

This is all on an '04 4 speed automatic.

 

I'm guessing that you had an evap emissions code. Gas cap is not always the fix for that. It is just a very cheap and easy guess. Chances are somebody forgot one of the evap vacuum lines or there is a crack in one of them.

Double check ALL the vacuum lines very carefully.

 

if the cel is on and the reader doesnt see any codes than either the reader is incompatible, the user is incompetent or you pcm or dash is fried

 

I'm guessing the reader is incompatible then. The user said he has done it a thousand times before and said that it was probably something wrong with the reader.

I don't believe this is the problem at the moment, it would have shown a code, as it did show a code before.

I went to AutoZone before and the reader worked and showed the codes for the evap system. My thoughts now are that something is fried or the code that is showing now isn't able to show on the reader at AutoZone. Would the PCM being fried result in more problems than just the CEL being on with no codes? Also, could a read just not be compatible with certain codes?

 

Cel on with no code(s) is unusual. It could be a defective or fried pcm. I am guessing its the pcm.

 

My guess would be that a different reader would pull the codes fine.

They're tricky little *******!