FREE REPAIR MANUALS & LABOR GUIDES 1982-2013 Vehicles
Courtesy of Operation CHARM: Car repair manuals for everyone.

High CO and HC - at Idle


This condition, at idle, indicates abnormally high Carbon Monoxide and Hydrocarbons.

POSSIBLE CAUSE ACTION


VERY RICH Air-Fuel mixture


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



Faulty Fuel Evaporative system, Check Fuel Evaporative system
vapor lines, purge solenoid in "Testing Procedures" in Emissions
and valves



Fuel in crankcase being Remove PCV from crankcase
sucked through PCV valve and retest emissions



Engine misfire with Closed Loop Refer to "Fuel Injection and
fuel metering, causing system Computerized Engine Controls"
to go full rich for rich trouble code,
check fuel feedback (Oxygen sensor)