Conditions For Running DTC
WARNING: This page is about a different car, the 2002 Pontiac Firebird and 2002 Chevrolet Camaro. However, it is still accessible from the selected car via links, so may be relevant.
- Meet the conditions for engine warm up.
- DTCs P0101-P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0125, P0130-P0135, P0137, P0138, P0140, P0141, P0150-P0155, P0171, P0172, P0174, P0175, P0201-P0206, P0300, P0325, P0336, P0341, P0401, P0403-P0405, P0440, P0442, P0443, P0446, P0449, P0502, P0503, P0506, P0507, P1120, P1125, P1133, P1134, P1153, P1154, P1220, P1221, P1336, P1352, P1361, P1362, P1441, or P1523 are not set.
- The engine has been running longer than 10 minutes.
- The Engine Coolant Temperature (ECT) is between 158-255°F (70-124°C).
- The Barometric (BARO) pressure is more than 75 kPa.
- The vehicle is in Closed Loop.
- The IAT is between -4-212°F (-20-100°C).
- The battery voltage more than 10.7 volts.
- Warm the catalyst.
- Fully open the hood.
- Place the transmission in Park for an A/T, or in Neutral for a M/T.
- Set the parking brake.
- Press and hold the service brake.
- Each time the engine is started, the diagnostic can run up to 18 times. After the 10 minute run time, and before the diagnostic runs the first time, the engine must run an additional 5 minutes between 1500-2000 RPM. For any additional tests on the same key cycle, the RPM must be between 1500-2000 RPM for 1 minute.
- In order to activate the diagnostic, return the engine to idle, and put the vehicle in Drive for an A/T, or depress the clutch for a M/T.
- Test the catalyst.
- Place the transmission in Drive for an A/T, or in Neutral and depress the clutch for a M/T.
- Within 60 seconds, the air/fuel ratio will go rich, below 14.0:1, for up to 5 seconds, then the air/fuel ratio may go lean, above 15.3:1, for up to 8 seconds.
- Use the scan tool in order to check if DTC P0420 has passed or failed this key cycle.