High CO, Low or Normal HC -- at Idle

Condition at idle: 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
Refer to FUEL SYSTEMS.



Dirty air filter(s) Clean or replace




Saturated fuel evaporative canister
or malfunctioning vapor purge system Check EVAP system.




Malfunctioning Closed Loop fuel metering Refer to COMPUTERIZED ENGINE CONTROLS
system - Exhaust leak or other false
indicators "Fooling" oxygen sensor to
sense a lean condition





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