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 system in
or malfunctioning vapor purge system "Testing Procedures" in Emissions



Malfunctioning Closed Loop fuel Refer to "Fuel Injection and
metering system - Exhaust leak Computerized Engine Controls"
or other false indicators for testing of the computer
"Fooling" oxygen sensor to feedback system
sense a lean condition



Stuck or restricted PCV Check PCV system in "Testing
valve and/or hose Procedures" in Emissions