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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Cobalt 🢒 Engine 🢒 Engine Controls - 2.0L 🢒 Inspection/Maintenance (I/M) Catalyst System Set Procedure

Description

The purpose of this procedure is to satisfy the enable criteria necessary in order to execute the inspection/maintenance (I/M) readiness diagnostics for the Catalyst System. Ensure the vehicle meets the requirements listed in Conditions for Running before performing this test. Failure to meet the necessary requirements may produce inaccurate test results.

Conditions for Running
    • The catalytic temperature is between 535-675°C (995-1,247°F).
    • The barometric pressure (BARO) is more than 72 kPa.
    • Engine coolant is at operating temperature, 69-125°C (156-257°F).
    • The intake air temperature (IAT) is between -20 and +80°C (-4 and +176°F).
    • The engine is in Closed Loop fuel control.
    • The battery voltage is more than 11 volts.

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 can be repeated until the I/M System Status updates to YES.

The I/M System Status does not indicate whether the test has passed or failed, only that a decision was made. 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 required tests have not run. When a failure occurs, the Emission Related DTC portion of the I/M System Status display will indicate the MIL is requested. The I/M System Status also registers the number of diagnostic trouble codes (DTCs).

The first failure of a type B DTC does not constitute a final determination of pass or fail, and will not update the I/M System Status to YES. A second trip is required, and all the conditions to run must be met in order for the test to run again. These conditions may include a partial to complete engine cool down.

The I/M System Status will update only when the DTC fails the second time, or when all of the tests pass.

If there is an impending failure, the system may require more time to run the diagnostic than was allotted in the set procedure. If the test does not run after numerous attempts, and if no DTC is set, review the appropriate scan tool data list and review the service information for an indication of why the test does not complete. Some tests may abort due to changes in the conditions while the test is running. For example, changes in engine load such as a cooling fan or an A/C compressor clutch turning on may cause the test to abort.

If a diagnostic test is difficult to run, observe the I/M System Status display while maintaining the necessary enable conditions until the 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 the engine to idle for 2 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:

  4. Acceleration at part throttle to 90 km/h (56 mph) with this speed maintained until the engine reaches operation temperature. This may take up to 10 minutes.
  5. Continue operating under these conditions for an additional 5 minutes after the engine reaches operating temperature.
  6. Deceleration to 0 km/h (0 mph).
  7. Engine idling for 2 minutes while the following criteria is maintained:
    8. • Service brake depressed
    • Manual transmission in Neutral with the clutch pedal depressed
  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 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

Go to Step 4

4

  1. Refer to 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. This may take up to 2 hours.
  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

System OK