Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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 procedure. 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 procedure.
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 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.
| System | DTCs Required To Set System Status To YES |
|---|---|
| AIR | DTC P0410 |
| Catalyst | DTC P0420 |
| EGR | DTCs P0401 , P0404 , P0405 & P1404 |
| EVAP | DTCs P0440 , P0442 , P0446 & P1441 |
| Oxygen Sensor | DTCs P0133 , P0140 (Except Regal) , P0140 (Regal) , P1133 & P1134 |
| Oxygen Sensor Heater | DTCs P0135 , P0141 (Except Regal) & P0141 (Regal) |
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.