Diagnostic Aids

Rough road conditions may prevent some tests from running. Extreme high or low ambient temperatures may prevent tests such as Heated Oxygen Sensor (HO2S) heater and Evaporative Emission (EVAP) system from initiating. If a step is interrupted before completion, perform remaining portion of set procedures. Any portion of set procedure that requires engine at operating temperature may be repeated. This allows most diagnostics to run and remaining tests can be performed using individual system set procedures.

If vehicle has recently run, start this procedure at step  3. This will allow tests that require the engine at operating temperature to run. Using this method allows shorter cool down periods if tests requiring a cold start do not initiate.

Scan tool can be used to monitor each I/M SYSTEM STATUS indicator during I/M complete system set procedure. When all of indicators for a test step have updated to YES, testing can move on to next step even if remaining portion of test is not complete. For example, step  3 is designed to run the EVAP, secondary Air Injection (AIR), and HO2S tests. Procedure instructs technician to operate vehicle in enable conditions for 6 minutes. If all 3 tests have updated to YES within 4 minutes, it is not necessary to continue with enable conditions and testing can advance to next step.