For 1990-2009 cars

### Circuit Description

The heated oxygen sensor (HO2S) heater reduces the time required for the oxygen sensor to reach operating temperature and maintains the operating temperature during extended idle periods. When the ignition is turned to the ON position, ignition voltage is supplied directly to the sensor heater. The engine control module (ECM) controls the heater operation by first modulating the control circuit to ground when the sensors are cold. This prevents the possibility of thermal shock to the sensor, from condensation build-up on the sensor, by controlling the sensor's rate of heating. After a predetermined amount of time, the ECM commands the heaters ON continuously. Once the sensor reaches operating temperature, the ECM may modulate the heater control circuit to ground to maintain a desired temperature.

The ECM controls the heater by grounding the control circuit with a solid state device called a driver. The driver is equipped with a feedback circuit that is pulled up to a voltage. The ECM can determine if a control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage. If the ECM detects the control circuit voltage is more than a predetermined value when the circuit is commanded ON, this DTC sets.

### DTC Descriptors

This diagnostic procedure supports the following DTCs:

• | DTC P0032 HO2S Heater Control Circuit High Voltage Bank 1 Sensor 1

• | DTC P0038 HO2S Heater Control Circuit High Voltage Bank 1 Sensor 2

• | DTC P0052 HO2S Heater Control Circuit High Voltage Bank 2 Sensor 1

• | DTC P0058 HO2S Heater Control Circuit High Voltage Bank 2 Sensor 2

### Conditions for Running the DTC

#### P0032 and P0052

• | Engine is running.

• | The ignition 1 voltage is between 10.5-18 volts.

• | The ECM has commanded the heated oxygen sensor (HO2S) heater ON and OFF at least once during the ignition cycle.

• | DTC P0032, P0052 run continuously once the above conditions are met.

#### P0038 and P0058

• | The engine speed is more than 80 RPM.

• | The ignition 1 voltage is between 10-18 volts.

• | Rear HO2S heater is ready.

• | Rear HO2S is near to frost state.

• | The ECM has commanded the HO2S heater ON and OFF at least once during the ignition cycle.

• | DTC P0038, P0058 run continuously once the above conditions are met.

### Conditions for Setting the DTC

• | The ECM detects a short to voltage in the heater circuits of the HO2S when the heater is commanded ON.

• | The condition exists for more than 4 seconds.

### 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 4 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

• | Use the J 35616-A/BT-8637 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector.

• | The lower connector of the ECM is connector C1 and the upper connector of the ECM is connector C2. Refer to Front of Vehicle/Engine Compartment Component Views.

• | If the condition is intermittent, move the related harnesses and connectors, with the engine operating, while monitoring the circuit status for the component with a scan tool. The circuit status parameter changes from OK or Indeterminate to Fault if there is a condition with the circuit or a connection. The ODM information is in the output driver module (ODM) data list.

• | Inspect the sensor pigtail or the harness for contacting the exhaust system.

• | For an intermittent condition, refer to Intermittent Conditions.

### Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. The engine must be running for the ECM to operate the control circuit.

2. Inspect the HO2S connector for water intrusion, corrosion, and bent or damaged terminals.

3. Inspect the ECM connectors for water intrusion, corrosion, and bent or damaged terminals.

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: Engine Controls Schematics Connector End View Reference: Component Connector End Views
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. Start the engine.
2. Allow the engine to idle for at least 30 seconds.
3. Observe the DTC information with a scan tool.

Does DTC P0032, DTC P0038, DTC P0052, or DTC P0058 fail this ignition?

Go to Step 4

Go to Step 3

3 |

1. Observe the Freeze Frame/Failure Records for this DTC.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

Go to Step 4

Go to Diagnostic Aids

4 |

1. Turn OFF the ignition.

Note: The ignition must be OFF when disconnecting or connecting the heated oxygen sensors (HO2S) electrical connector.

2. Disconnect the appropriate HO2S.
3. Connect a test lamp between the heater control circuit of the HO2S and the ignition 1 voltage circuit of the HO2S.
4. Start the engine.

Does the test lamp illuminate?

Go to Step 6

Go to Step 5

5 |

1. Turn OFF the ignition.
2. Disconnect the engine control module (ECM).
3. Test the heater control circuit between the HO2S and the ECM for a short to voltage. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

Go to Step 10

Go to Step 7

6 | Test for shorted terminals and poor connections at the HO2S. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct the condition? | Go to Step 10 | Go to Step 8
7 | Test for shorted terminals and poor connections at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct the condition? | Go to Step 10 | Go to Step 9
8 | Replace the HO2S. Refer to the appropriate procedure:

• | Heated Oxygen Sensor Replacement - Bank 1 Sensor 1

• | Heated Oxygen Sensor Replacement - Bank 1 Sensor 2

• | Heated Oxygen Sensor Replacement - Bank 2 Sensor 1

• | Heated Oxygen Sensor Replacement - Bank 2 Sensor 2

Did you complete the replacement?

Go to Step 10

--

9 | Replace the ECM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 10 | --
10 |

1. Clear any DTCs with a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

Go to Step 2

Go to Step 11

11 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | Go to Diagnostic Trouble Code (DTC) List - Vehicle | System OK