GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2005 🢒 LeSabre 🢒 Engine 🢒 Engine Controls - 3.8L (L36 and L67) 🢒 Inspection/Maintenance (I/M) Catalyst System Set Procedure

Description

The purpose of this test is to satisfy the enable criteria necessary to execute inspection/maintenance (I/M) readiness diagnostics for the catalyst system. The test may be used to set the I/M System Status indicators to YES. The I/M System Status display on the scan tool provides an indication of whether the control module has completed the required tests. The I/M System Status does not indicate that the tests have passed or failed. When all of the diagnostics for a specific system have run and passed, the I/M System Status will update to YES. If a test for a specific system has failed, the I/M System Status will update to YES, indicating a determination was made even if all of the other tests for that system have not run.

Conditions for Running
    • The engine has been running longer than 10 minutes.
    • The engine load must be stable.
    • The idle air control (IAC) position parameter does not change more than 5 counts.
    • The throttle position is below 1.5 percent.
    • The short term fuel trim (FT) is between -20 and +20 percent.
    • The transaxle is in drive for automatic transaxles, or in neutral for manual transaxles with the clutch pedal depressed.
    • The barometric pressure is more than 74 kPa.
    • The engine coolant temperature (ECT) is between 75-126°C (167-258.8°F).
    • The engine is in Closed Loop fuel control.
    • The battery voltage is more than 10.7 volts.
    • The intake air temperature (IAT) is between -20 and +100°C (-4 and +212°F).
    • The difference between the engine speed and the desired engine speed is less than 200 RPM.
    • The mass air flow (MAF) is between 3-10 grams per second.

Diagnostic Aids

The control module runs a maximum of 6 tests per trip until the Catalyst System Status updates to YES. If the status does not update, the test outlined in this procedure may be repeated until the I/M System Status updates to YES.

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 the vehicle is within the Conditions for Running specified in the supporting text.
  2. Turn OFF all of the accessories, e.g., A/C, blower fan, etc.
  3. Start the engine and allow it to idle for 5 minutes.

    4. Caution: Refer to Road Test Caution in the Preface section.

    Important:  In order for this test to run, the vehicle must operate in the following conditions:

       • Acceleration at part throttle to 90 km/h (55 mph) with this speed maintained for 10 minutes
       • Deceleration to 0 km/h (0 mph)
       • Engine idling for 2 minutes while the following criteria is maintained:
          - Service brake depressed
          - Automatic transmission in Drive
          - Manual transmission in Neutral with the clutch depressed

  4. 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. Refer to the Inspection/Maintenance (I/M) System DTC Table to determine which DTCs are required to run in order to complete this test.
  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