Conditions for Updating the I/M System Status

Each system requires at least one, and sometimes several, diagnostic tests. Results of these tests are reported by a Diagnostic Trouble Code (DTC). A system monitor is complete when either all DTCs comprising the monitor have run and passed, or when any one of the DTCs comprising the monitor has illuminated the Malfunction Indicator Light (MIL). Once all tests are completed, I/M System Status display will indicate YES. Example: when HO2S Heater Test indicates YES, all oxygen sensor heaters have been diagnosed. I/M System Status will indicate NO when any of the required tests for that system have not run. The following conditions will set I/M system status indicator to NO:

• Vehicle is new from factory and has not yet been driven through necessary drive conditions to complete tests.
• Battery has been disconnected or discharged below operating voltage.
• PCM power or ground has been interrupted.
• PCM has been reprogrammed.
• PCM DTCs have been cleared as part of a service procedure.