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,
Fuel Injected perform injector balance test,
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"




Malfunctioning Closed Loop fuel metering Test the Fuel Injection System
system - Exhaust leak or other false
indicators "Fooling" oxygen sensor to
sense a lean condition





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