Possible Causes
- Engine malfunction.
- Exhaust system leak.
- Front HO2S deterioration.
- Front HO2S heater malfunction.
- Fuel filter plugged or restricted.
- Fuel leak at fuel line or return line.
- Fuel pressure regulator malfunction.
- Fuel pump malfunction.
- Low engine compression.
- Pressure Regulator Control (PRC) solenoid valve malfunction.
- Purge solenoid hoses improperly connected.
- Purge solenoid valve malfunction.