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.
- Leaking fuel injector(s).
- Leaking fuel pressure regulator.
- Low fuel pressure or running out of fuel.
- Contaminated fuel injector(s).
Inductive System
- Air leaks after Mass Airflow/Intake Air Temperature (MAF/IAT) sensor.
- Vacuum leaks.
- PCV system.
- Improperly seated engine oil dipstick.
EGR System
- Leaking gasket.
- Stuck open EGR valve.
- Leaking EGR diaphragm.
Base Engine
- Engine oil overfill.
- Cam timing.
- Cylinder compression.
- Exhaust leaks before or near HO2S.