Possible Causes
WARNING: This page is about a different car, the 2003 Mazda Protege5 and 2003 Mazda Protege. However, it is still accessible from the selected car via links, so may be relevant.
- PCM malfunction.
- Rear HO2S malfunction
- Short to power between rear HO2S and PCM.
- Shorted rear HO2S or PCM.