Conditions For Running DTC (Except LeSabre)
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- Meet conditions for engine warm up. Using scan tool in catalyst data list, verify the following:
- DTCs P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0125, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0141, P0171, P0172, P0201-P0206, P0300, P0325, P0327, P0336, P0341, P0401, P0403, P0404, P0405, P0440, P0442, P0443, P0446, P0449, P0502, P0503, P0506, P0507, P1133, P1134, P1336, P1351, P1352, P1361, P1362, P1374, P1404, or P1441 are not set.
- Engine has been running more than 10 minutes.
- Engine Coolant Temperature (ECT) is 158-255°F (70-124°C).
- Barometer (BARO) is more than 75 kPa.
- Vehicle is in closed loop.
- Intake Air Temperature (IAT) is more than -4 to 212°F (-20 to 100°C).
- Battery voltage is more than 10.7 volts.
- Warm up catalyst.
- Fully open the hood.
- Set transmission is in Park (A/T) or in Neutral (M/T).
- Set parking brake.
- Press and HOLD service brake.
- Each time engine is started, diagnostic can run up to 18 times. After 10-minute run time and before diagnostic runs first time, engine must run an additional 5 minutes between 1500-2500 RPM. Any additional tests on same key cycle, engine speed must be 1500-2500 RPM for one minute.
- To activate diagnostic, return engine to idle and put vehicle in Drive, or depress clutch for a manual transmission.
- Test catalyst.
- Transmission in Drive (A/T) or in Neutral (M/T with clutch depressed).
- Within 60 seconds, the air fuel ratio will go lean below 14.1 for up to 7 seconds, and then may go rich, above 15.3, for up to 7 seconds.
- Use the scan tool in order to determine if DTC P0420 has passed or failed this key cycle.