Circuit Description
The heated oxygen sensor (HO2S) heater is a device used to reduce the time that the sensor takes to go active. The HO2S bank 1 sensor 2 heater helps maintain proper sensor temperature for catalyst testing, and fuel trim adjustments. The heater receives power through a fused ignition circuit. The powertrain control module (PCM) uses a low side driver (ODM) to turn the heater ON and OFF. The PCM monitors the circuit for conditions that are incorrect for the commanded state of the low side driver. If the PCM detects an incorrect circuit conditions, this diagnostic trouble code (DTC) will set.
Conditions for Running the DTC
| • | The 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 low side driver.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Diagnostic Aids
If the condition is intermittent, refer to Intermittent Conditions .
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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If the DTC sets with the ignition ON, this indicates the bank 1 sensor 2 heater low circuit is shorted to ground or open. If the HO2S fuse is open, the starter will not engage. Ensure you test all related circuits for a short to ground.
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If the DTC sets with the engine operating, this indicates the bank 1 sensor 2 heater low circuit is shorted to a voltage.
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An open HO2S fuse causes multiple DTCs to set. If the fuse is open, the starter will not engage. Ensure you test all related circuits for a short to ground.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 4 | |
Does DTC P0036 set? | -- | Go to Step 4 | Go to Step 3 | |
Important: If the engine does not crank, go to Step 4. Does DTC P0036 set? | -- | Go to Step 9 | Go to Intermittent Conditions | |
4 | Is OXY SEN 2 fuse open? | -- | Go to Step 5 | Go to Step 6 |
Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 14 | |
6 |
Does the test lamp illuminate? | -- | Go to Step 7 | Go to Step 13 |
7 | With a DMM, measure the voltage at the HO2S bank 1 sensor 2 heater low control circuit. Is the voltage near the specified voltage? | 2 V | Go to Step 11 | Go to Step 8 |
8 |
Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 12 |
9 |
Is the voltage near the specified value? | 2 V | Go to Step 14 | Go to Step 10 |
10 | Test the HO2S bank 1 sensor 2 heater low control circuit for a short to voltage. Refer to Circuit Testing , and refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 15 |
11 | Inspect for poor connections at the harness connector of the HO2S bank 1 sensor 2. Refer to Testing for Intermittent Conditions and Poor Connections , and refer to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 14 |
12 | Inspect for poor connections at the harness connector of the PCM . Refer to Testing for Intermittent Conditions and Poor Connections , and refer to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 15 |
13 | Repair the open HO2S bank 1 sensor 2 ignition 1 voltage circuit. Did you complete the repair? | -- | Go to Step 16 | -- |
14 | Replace HO2S bank 1 sensor 2. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 . Did you complete the replacement? | -- | Go to Step 16 | -- |
15 | Replace the PCM. Refer Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 16 | -- |
16 |
Does the DTC run and pass? | -- | Go to Step 17 | Go to Step 4 |
17 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |
