The heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream. The HO2S must reach operating temperature to provide an accurate voltage signal. A heating element inside the HO2S minimizes the time required for the sensor to reach operating temperature. Voltage is provided to the heater by the ignition 1 voltage circuit through a fuse. Ground is provided to the heater on the low control circuit by a low side driver within the control module.

The HO2S utilizes the following circuits:

The HO2S 2 heater circuit current flow is outside the expected value for the calculated internal temperature of the sensor.

DTC P0141 is a Type B DTC.

DTC P0141 is a Type B DTC.

The HO2S Heater diagnostic can be monitored on the scan tool under the I/M System Information selection of System Information. When the HO2S Heater test displays a YES status, indicating that the oxygen sensor heater diagnostic is completed, check for a DTC P0031, P0032, P0037, or P0038. If there is no DTC displayed the HO2S heater diagnostic has run and passed, indicating that no malfunction was present this time. The DTCs MUST be cleared in order to view the Current Status of the system diagnostics being performed. Do not forget that I/M System Information tests only indicate that the test has run, not whether the test passed or failed.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Important: It may take up to 8 minutes for the DTC to set.

1. Engine at normal operating temperature, operate the engine above 1,200 RPM for 30 seconds and then allow the engine to idle. DTC P0141 should not set.
2. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

1. Ignition OFF, disconnect the harness connector at the appropriate HO2S.
2. Ignition ON, verify that a test lamp illuminates between the ignition 1 voltage circuit terminal 2 and ground.

⇒	If the test lamp does not illuminate, test the ignition 1 voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition 1 voltage circuit fuse is open, test all components connected to the ignition 1 voltage circuit and replace as necessary.

3. Ignition OFF, connect the HO2S circuits together with four 10 amp fused jumper wires.

Important: The following test must be performed with both the HO2S sensor and the control module connected and operating normally.

4. Ignition ON, verify a test lamp illuminates between the control circuit terminal 1 and ground.

⇒	If the test lamp does not illuminate, test the heater control circuit for a short to ground or a short to voltage. If the circuit tests normal, test or replace the HO2S sensor.

Important: 

•	The following test must be performed with both the HO2S sensor and the control module connected and operating normally.

•	The test lamp must still be connected to ground and the heater control circuit.

5. Engine running for one minute, observe the test lamp. The test lamp should flash ON and OFF during the first 30 seconds of the engine running.

⇒	If the test lamp is always ON, test for an open/high resistance in the heater control circuit.

6. If all circuits test normal, replace the PCM.

1. Ignition OFF, disconnect the harness connector at the HO2S.
2. Test for 11 to 16 ohms at 20°C (68°F) between the ignition 1 voltage terminal 1 and the heater control terminal 2.

⇒	If not within the specified range, replace the HO2S sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.