Possible Causes
WARNING: This page is about a different car, the 2003 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.
Possible causes are:
- Engine malfunction
- Front HO2S deterioration
- Front HO2S heater malfunction
- Insufficient compression
- Leakage exhaust system
- Open or short circuit to ground in Black wire between front HO2S 4-pin harness connector terminal "A" and PCM 30-pin harness connector terminal "1AB"