High CO, Low or Normal HC - at Idle

This condition, at idle, is indicated by abnormally high carbon monoxide emissions while the hydrocarbon emissions remain normal or low.

POSSIBLE CAUSE ACTION

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



Dirty air filter(s) Clean or replace



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



Malfunctioning Closed Loop Fuel metering Check the computer
system. Exhaust leak or other condition feedback system
causing false lean oxygen sensor signal
to ECM.



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