High CO, Low or Normal HC - at Idle

This condition, abnormally high Carbon Monoxide while the Hydrocarbons remain normal or low, at idle may indicate a problem in one or more of the areas listed below.

POSSIBLE CAUSE ACTION
Rich operating condition


Feedback system not operating ^ Check oxygen sensor and feedback system.
in closed loop Refer to COMPUTERS AND CONTROL SYSTEMS

Excessive fuel pressure ^ Check fuel pressure regulator and return line.

Leaking fuel injector(s) ^ Refer to INJECTOR BALANCE CHART C-2A.



Dirty air filters ^ Clean or replace.



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



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