LEMON Manuals: Even more car manuals for everyone
Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 101 (Engine Control System Self-Diagnostics - 3.4L) >> Diagnostic Tests >> DTC P0420: TWC System Low Efficiency (Bank 1) >> Conditions For Running DTC

Conditions For Running DTC

WARNING: This page is about a different car, the 2002 Pontiac Grand Am, 2002 Oldsmobile Alero, 2002 Chevrolet Monte Carlo, and 2002 Chevrolet Impala. However, it is still accessible from the selected car via links, so may be relevant.
  1. Meet the conditions for engine warm up. Use the scan tool catalyst data list in order to verify the following conditions:
    • DTCs P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0125, P0131, P0134, P0135, P0137, P0138, P0140, P0141, P0171, P0172, P0201, P0202, P0203, P0204, P0205, P0206, P0300, 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.
    • The engine has been running for more than 10 minutes.
    • The ECT is 158-255°F (70-124°C).
    • The BARO is more than 75 kPa.
    • The vehicle is in Closed Loop.
    • The IAT is -4 to 212°F (-20 to 100°C).
    • The battery voltage is more than 10.7 volts.
  2. Warm the catalyst:
    • Fully open the hood.
    • Place the transmission in Park (A/T) or in Neutral (M/T).
    • Set the park 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 1500-2500 RPM. For any additional tests on the same key cycle, the engine must be between 1500-2500 RPM for 1 minute.
    • In order to activate the diagnostic, return to idle and place the vehicle in Drive (A/T), or depress the clutch pedal (M/T).
  3. Test the catalyst:
    • Verify that the transaxle is in Drive (A/T) or is in Neutral with the clutch pedal depressed (M/T).
    • Within 60 seconds, the air fuel ratio will go lean less than 14.1 for up to 7 seconds, and then may go rich, greater than 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.
scientia non olet · About LEMON Manuals