Diagnostic Aids

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

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

Scan tool can be used to monitor each I/M system status indicator. When all indicators for a test step have updated to YES, testing can move on to next step even if remaining portion of the test is not complete. For example, step  3 is designed to run EVAP, AIR, and HO2S tests. The procedure instructs technician to operate the vehicle in enable conditions for 6 minutes. If all 3 tests have updated to YES within 4 minutes, you do not need to continue with the enable conditions and testing can advance to the next step.