Conditions For Updating I/M System Status

Each system requires at least one, sometimes several, diagnostic tests. Results of these tests are reported by a Diagnostic Trouble Code (DTC). System monitor is complete when either all DTCs comprising monitor have run and passed, or any one DTC comprising monitor have illuminated the Malfunction Indicator Light (MIL). Once all tests are completed, I/M System Status display will indicate YES in COMPLETED column.

For example, when HO2S Heater Test indicates YES, all oxygen sensor heaters have been diagnosed. If vehicle has four heated oxygen sensors, all four heater circuits have been diagnosed. I/M System Status will indicate NO under COMPLETED column when any required tests for that system have not run.

Following is a list of conditions that would set I/M System Status indicator to NO:

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