Possible Causes
WARNING: This page is about a different car, the 2003 Mazda B4000, 2003 Mazda B3000, and 2003 Mazda B2300. However, it is still accessible from the selected car via links, so may be relevant.
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).