Conditions for Running the DTC
WARNING: This page is about a different car, the 2004 Pontiac Aztek and 2004 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.
- DTCs P0030, P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0125, P0128, P0130, P0131, P0132, P0133, P0134, P0135, P0136, P0137, P0138, P0140, P0141, P0171, P0172, P0201-P0206, P0300, P0336, P0341, P0404, P0405, P0442, P0443, P0455, P0496, P0502, P0503, P0506, P0507, P1133, P1134, P1351, P1352, P1361, P1362 are not set.
- The engine has been running longer than 10 minutes.
- The engine coolant temperature (ECT) is between 75-167°C (169-255°F).
- The barometric pressure (BARO) is above 74 kPa.
- The vehicle is in Closed Loop.
- The intake air temperature (IAT) is between -20 to +100°C (-4 to +212°F).
- The engine load must be stable.
- The engine speed is within 150 RPM above or 127 RPM below the desired idle.
- The throttle position (TP) is below 1.5 percent.
- The short term fuel trim (FT) is between -1.5 and +1.5 percent.
- The battery voltage above 10.7 volts.
- The catalyst test will abort if the vehicle falls outside the conditions listed above while the test is running.
- Warm up the catalyst.
- Fully open the hood.
- The transmission is in Park, automatic, or Neutral, manual.
- Set the parking brake.
- Press and hold the service brake.
- Each time the engine is started, the diagnostic can run up to 18 times if the tests are a combination of passes and failures. If each subsequent test is a pass the diagnostic will run a maximum of 6 times. After the 10 minute run time, and before the diagnostic runs the first time, the engine must run an additional 3 minutes between 1,500-2,500 RPM. For any additional tests on the same key cycle, the engine must be between 1,500-2,500 RPM for 1 minute.
- In order to activate the diagnostic, return the engine to idle and place the vehicle in drive.
- Test the catalyst.
- The transaxle is in drive.
- Within 60 seconds the air/fuel ratio will transition rich, below 13.7, for up to 7 seconds. The air/fuel ratio may then transition lean, above 16, for up to 7 seconds.
- Using the scan tool, check and see if DTC P0420 has passed or failed this key cycle.