High CO, Low or Normal HC - at Idle

Condition: High Carbon Monoxide, normal or low Hydrocarbons at idle.

POSSIBLE CAUSE ACTION


Rich Air-Fuel mixture Check fuel pressure.
Check O2 sensor.
Perform injector balance test (MPI).

Dirty air filter Clean or replace

Saturated fuel evaporative canister Check Evaporative system.
or malfunctioning vapor purge system Evaporative Emissions System

Stuck or restricted PCV valve and/or hose Check PCV system.
Positive Crankcase Ventilation