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
or malfunctioning vapor purge system Evaporative system, Evaporative Emissions System

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