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Home >> Buick >> 2005 >> Allure CX >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - 3.8L (Troubleshooting & Diagnosis) >> Troubleshooting >> Inspection/Maintenance (I/M) Catalyst System Set Procedure >> Test Description
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Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. 1:  Perform the I/M System Check before performing this test. Failure to do so may result in difficulty updating the status to YES.
  2. 2:  The Catalyst Test during the idle period immediately following the cruise period.
  3. 3:  This step identifies a first failure of a type B DTC. A DTC only appears on the I/M System Status display when the DTC becomes a MIL illuminating DTC. This occurs on the second failure of a type B DTC. A first failure of a type B DTC will not allow the I/M System Status to update to YES. Refer to Diagnostic Aids.
  4. 4:  This step helps to identify any unique or unusual criteria required to run the diagnostic test in the event the universal set procedure does not. This information is located in the service information under Conditions for Running the DTC.
  5. 5:  The I/M System Status only reports on whether or not a diagnostic has run, not what the outcome of the test was. If any Emission Related DTC sets after the tests are complete, the DTC will require diagnosis.
Inspection/Maintenance (I/M) Catalyst System Set Procedure

Step Action Yes No
1  Did you perform the Inspection/Maintenance (I/M) System Check? Go to Step 2  Go to Inspection/Maintenance (I/M) System Check 
2 
  1. Ensure that the vehicle is within the Conditions for Running, as specified in the supporting text.
  2. Turn OFF all of the accessories, such as the A/C, the blower fan, etc.
  3. Start and idle the engine.
    4. IMPORTANT: The vehicle must operate in the following conditions in order for this test to run:
  4. Acceleration at part throttle to 90 km/h (55 mph) with this speed maintained for 5 minutes
  5. Deceleration to 0 km/h (0 mph)
  6. Engine idling for 2 minutes while the following criteria is maintained:
    • The service brake is depressed.
    • The automatic transmission is in Drive.
    • The manual transmission is in Neutral with the clutch pedal depressed.
  7. Observe the I/M System Status display with a scan tool.
Did the Catalyst System Status update to YES?		 Go to Step 5  Go to Step 3 
3  Observe the DTC Information with a scan tool.
Does the scan tool indicate any failed DTCs?		 Go to Diagnostic Trouble Code (DTC) List - Vehicle In Vehicle DTC Information Go to Step 4 
4 
  1. Determine which DTCs are required to run in order to complete this test. Refer to DTC P0420 .
  2. Observe the Not Ran Since Code Cleared display with a scan tool.
  3. Determine which of the DTCs required for a YES status has not run.
  4. Enter the DTC number in the Specific DTC menu of the scan tool.
  5. Operate the vehicle within the Conditions for Running the DTC, located in the supporting text for the diagnostic table of the DTC.
  6. Repeat the procedure until the scan tool indicates the diagnostic test has run.
  7. Repeat steps 4-6 for any additional required DTCs that have not run.
  8. Observe the I/M System Status display with a scan tool.
Did the Catalyst System Status update to YES?		 Go to Step 5  Go to Diagnostic Aids
5  Observe the Emission Related DTC portion of the I/M System Status display with a scan tool.
Does the scan tool indicate any Emission Related DTCs set?		 Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information System OK
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