Code Enable Criteria

1. Meet conditions for engine warm up. Using scan tool in catalyst data list, verify the following:
   • 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 -4-212°F (-20-100°C).
   • Battery voltage is more than 10.7 volts.
   • DTCs P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0130, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0141, P0171, P0172, P0201-206, P0300, P0336, P0341, P0401, P0403, P0404, P0405, P0410, P0412, P0418, P0440, P0442, P0443, P0446, P0449, P0502, P0503, P0506, P0507, P1133, P1134, P1336, P1351, P1352, P1361, P1374, or P1441 are not set.
2. 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.
3. Test catalyst.
   • Transmission in Drive (A/T) or in Neutral (M/T with clutch depressed).
   • With VIN K California emissions, within 60 seconds, air/fuel ratio will go rich less than 14.1 for up to 6 seconds. Then air/fuel ratio may go lean more than 15.3 for up to 8 seconds.
   • With VIN K FED emissions, within 60 seconds, air/fuel ratio will go lean more than 15.3 for up to 6 seconds, then may go rich less than 14.1 for up to 7 seconds.
   • With VIN 1, within 60 seconds, air/fuel ratio will go rich less than 14.1 for up to 7 seconds. Then air-fuel ratio may go lean more than 15.3 for up to 9 seconds.
   • Using scan tool, check if DTC P0420 has passed or failed this key cycle.

DTC sets when PCM determines catalysts oxygen storage capacity is less than an acceptable threshold.