Possible Causes
Possible causes are:
Fuel System
- Excessive fuel pressure.
- Vapor recovery system.
Induction System
- Restricted air intake.
- PCV system.
- Improperly seated engine oil dipstick.
EGR System
- Leaking EGR gasket.
- Stuck EGR valve.
- Leaking EGR diaphragm or EGR vacuum regulator.
Base Engine
- Engine oil overfill.
- Engine cam timing.
- Cylinder compression.
- Exhaust leaks before or near HO2S(s).