Description
The purpose of this procedure is to satisfy the enable criteria necessary to execute an Inspection/Maintenance (I/M) System monitor for the Heated Oxygen Sensor (HO2S) Heater System. The system monitor is comprised of the test results from one or more DTCs. This procedure may be used to set the HO2S Heater I/M System Status display on the scan tool to YES. The HO2S Heater I/M System Status display indicates whether or not the control module has completed the system monitor. The system monitor completes when either all DTCs comprising the monitor run and pass, or any DTC comprising the monitor illuminates the malfunction indicator lamp (MIL). If one of the DTCs comprising the monitor is set and the MIL is not illuminated, the necessary trips are required to illuminate the MIL before the monitor will complete. Once the monitor completes, the HO2S Heater I/M System Status display will be updated to YES.
Conditions for Running
| • | The start-up engine coolant temperature (ECT) is between -30 and +45°C (-22 and +113°F). |
| • | The difference between the start-up ECT and the start-up intake air temperature (IAT) is less than 8°C (14.4°F). |
Diagnostic Aids
The following is a list of conditions that require an 8 hour period without the engine starting, before the HO2S Heater I/M System Status will update to YES:
| • | The battery has been disconnected or discharged below operating voltage. |
| • | The control module power or ground has been interrupted. |
| • | The control module has been reprogrammed. |
If there is an impending failure, the system may require more time than was allotted in the system set procedure. If any DTCs do not run and no DTC is set, review the appropriate scan tool data list and service information. This will give an indication of why the DTCs do not run. Some may abort due to changes in the conditions while running. For example, changes in engine load, such as a cooling fan or A/C compressor clutch turning ON, may cause a DTC to abort. If the System Status does not update to YES, the procedure can be repeated until a YES status is achieved.
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? | 3 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 |
