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Home >> Buick >> 2008 >> Lucerne CXS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls And Fuel - 4.6L - DTC P0340 To DTC P2138 >> DTC P0420 >> Repair Verification

Repair Verification

  1. Clear all DTCs and allow the engine coolant temperature to reach 40°C (104°F).
  2. Drive the vehicle under the Conditions for Running the DTC.
  3. Verify that DTC P0420 has passed this ignition cycle.
    • If not passed or failed this ignition cycle, the test may have aborted resulting in an inconclusive test result. The above test may need to be repeated up to 5 more times during this drive cycle. The first test should be run after the initial warm-up period of 2 minutes. Between subsequent tests, maintain a steady vehicle speed of greater than 25 mph for 2 minutes.
  4. If 6 tests have been attempted and the DTC has not run or passed during this key cycle, turn the key to OFF for 90 seconds, then run the procedure a second time.
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