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

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.

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

1. Ignition OFF, connect a test lamp between ground and the control module HO2S 2 heater control circuit terminal X2-29.
2. Start and idle the engine for one minute while observing 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 PCM oxygen sensor ground circuit terminal X2-6. If the circuit tests normal, replace the PCM.

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

⇒	If not within the specified value, replace the HO2S 2.

5. Test the HO2S 2 heater control circuit terminal 2 for high resistance.

⇒	If the circuit tests normal, replace the PCM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.