Description
The purpose of this test is to satisfy the enable criteria necessary to execute I/M readiness diagnostics for the heated oxygen sensor (HO2S) system. The test may be used to set the I/M System Status to YES. The I/M System Status display on the scan tool provides an indication of whether the control module has completed the required test. The required test is complete when either all of the DTCs comprising the test have Run and Passed, or when any one of the DTCs comprising the test has illuminated the malfunction indicator lamp (MIL). Once the test is complete, the I/M System Status display will indicate YES in the Completed column.
Conditions for Running
| • | The engine coolant temperature (ECT) is less than 45°C (113°F). |
| • | The battery voltage is between 11.6-16 volts. |
Diagnostic Aids
The HO2S Heater Tests will normally run within the 2 minutes allotted in the procedure. If there is an indeterminate condition, the test may take up to 2 hours on some vehicles before a decision of pass or fail is made. If the test does not update to YES, it may have aborted due to the loss of enabling conditions.
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 no DTC is set, review the appropriate scan tool data list and 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.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Inspection/Maintenance (I/M) System Check? | -- | Go to Step 2 | |
2 |
Important: Whenever the ignition is turned ON, ignition positive voltage is supplied to the HO2S heaters. After verifying the enable criteria, turn OFF the ignition for approximately 5 minutes to allow the sensors to cool before continuing with the test. Did the HO2S Heater System Status update to YES? | 2 minutes | 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 Step 4 | |
4 |
Did the HO2S Heater 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? | -- | System OK |
