Possible Causes

Possible causes are:

• Low fuel pressure or running out of fuel.
• Excessive fuel pressure.
• Leaking fuel injector(s).
• Leaking fuel pressure regulator.
• Vapor recovery system.
• Contaminated fuel injector(s).
• Air leaks after MAF/IAT sensor.
• Vacuum leaks.
• Restricted air intake.
• PCV system.
• Improperly seated engine oil dipstick.
• Leaking EGR gasket.
• Stuck EGR valve.
• Leaking EGR diaphragm or EGR vacuum regulator.
• Engine oil overfill.
• Engine cam timing.
• Cylinder compression.
• Exhaust leaks before or near HO2S(s).