Diagnostic Aids

WARNING: This page is about a different car, the 2002 Saturn LW200, 2002 Saturn L200, and 2002 Saturn L100. However, it is still accessible from the selected car via links, so may be relevant.

DTC indicates engine is running rich. Possible causes of a rich air/fuel mixture are:

Fuel pressure high.
Fuel injector(s) leaking.
HO2S1 contaminated.
Vacuum leak around MAP sensor.
EVAP purge solenoid stuck open.
Restricted exhaust or restricted air induction.

To verify system is running rich, use scan tool to monitor HO2S1 and HO2S2. If both sensors are more than 600 millivolts, system is running rich and oxygen sensors are probably not at fault.