GM Service Manual Online
For 1990-2009 cars only

System

DTCs Required to Set System Status to YES

Catalyst Monitor

If an I/M System Status indicator did NOT update to Completed during the Inspection/Maintenance (I/M) System Check , review each indicator and reference this table to determine each DTC associated with the I/M System Status Indicator. Each DTC listed below has specific conditions that must be met for the diagnostic to run. Included in these conditions are additional DTCs which, if set, will inhibit these DTCs from running. Reviewing and operating the vehicle within the Conditions for Running for each DTC listed below will allow the I/M System Status Indicators to transition to Completed.

Catalyst

DTC P0420

EVAP

    •  DTC P0442 or P0456
    •  DTC P0446
    •  DTC P0455
    •  DTC P0496

Oxygen Sensor

Oxygen Sensor Heater