GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Cobalt 🢒 Engine 🢒 Engine Controls - 2.0L 🢒 Inspection/Maintenance Heated Oxygen Sensor/Oxygen Sensor System Set

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 Oxygen Sensor/Heated Oxygen Sensor (O2S/HO2S) 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 fuel level is more than 10 percent.
    • The engine speed is between 1,000-3,500 RPM.
    • The engine coolant temperature (ECT) is more than 70°C (158°F).
    • The engine is running in Closed Loop fuel control.
    • The engine has been running for more than 200 seconds.
    • The battery voltage is between 10-16 volts.

Diagnostic Aids

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 that 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 malfunction indicator lamp (MIL) is requested. The I/M System Status also registers the number of 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 the 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.

  4. Operate the vehicle in the following conditions:
    5. • Acceleration at part throttle to 72-89 km/h (45-55 mph) with this speed maintained for 6 minutes.
    • Deceleration to 0 km/h (0 mph).
    • Maintain the following criteria for 2 minutes with the engine idling:
       - The service brake is depressed.
       - The manual transmission is in neutral with the clutch pedal depressed.
  5. Review the I/M System Status display with a scan tool.

Did the HO2S/O2S 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 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. 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 HO2S/O2S 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