Refer to Engine Control Schematics
Heated Oxygen Sensors
.
Circuit Description
The oxygen sensor heater is a device used to reduce the time that the sensor takes to go active. The PCM controls the fuel control oxygen sensor heaters using three separate drivers. With the engine running, the PCM turns ON the heaters using a high side, and a low side driver. This helps warm-up the oxygen sensors. The PCM uses a third driver to test the oxygen sensor heaters. This driver contains current monitoring circuitry, when used in a diagnostic sequence with the other drivers, indicates the condition of the heaters. The PCM monitors this driver for circuit conditions that are incorrect for the commanded state of the driver. If the PCM detects an incorrect circuit condition, DTC P1031 will set.
Conditions for Running the DTC
| • | System voltage is between 9-18 volts. |
| • | The ignition is ON. |
Conditions for Setting the DTC
The PCM detects an incorrect circuit condition for the commanded state of the current monitor driver.
Action Taken When the DTC Sets
| • | The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic has been run and failed. |
| • | The PCM will store conditions which were present when the DTC set as Freeze Frame and Fail Records. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn the MIL OFF during the third consecutive trip in which the diagnostic has been run and passed. |
| • | The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC can be cleared by using the scan tool Clear DTC Information function. |
Diagnostic Aids
If the condition is intermittent, refer to Intermittent Conditions in Symptoms.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | |
2 |
Are DTCs P0030, P1031, and P1032 set? | -- | Go to Step 3 | |
3 |
Are DTCs P1031 and P1032 set? | -- | Go to Step 4 | Go to Intermittent Conditions |
4 |
Does the test lamp turn ON and OFF? | -- | Go to Step 9 | Go to Step 5 |
5 |
Caution: Avoid contact with moving parts and hot surfaces while working around a running engine in order to prevent physical injury. Does the test lamp turn ON and OFF? | -- | Go to Step 8 | Go to Step 6 |
6 |
Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 7 |
7 | Test the HO2S bank 2 sensor 1 heater low circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 10 |
8 | Replace HO2S bank 2 sensor 1. Refer to Heated Oxygen Sensor Replacement - Bank 2 . Did you complete the replacement? | -- | Go to Step 11 | -- |
9 | Replace HO2S bank 1 sensor 1. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 . Did you complete the replacement? | -- | Go to Step 11 | -- |
10 |
Important: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | Go to Step 11 | -- |
11 |
Does the scan tool display the DTC ran and passed? | -- | System OK | Go to Step 2 |
