High CO, Low or Normal HC at Idle

DEFINITION: At idle indicates abnormally high Carbon Monoxide while the Hydrocarbons remain normal or low.

POSSIBLE CAUSE ACTION


Rich Air-Fuel mixture



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



Dirty air filters Clean or replace.



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