High CO, Low or Normal HC - at Idle

This condition, at idle, indicates abnormally high Carbon Monoxide while the Hydrocarbons remain normal or low.

POSSIBLE CAUSE ACTION


Rich Air-Fuel mixture ^ Check Air-Fuel ratio, O2 sensor, perform injector balance test, inspect regulator operation (check vacuum line and return hose), check fuel pressure.


Dirty air filters ^ Clean or replace


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


Stuck or restricted PCV valve and/or hose ^ Check PCV system.