GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P0141:  HO2S Heater Performance Sensor 2

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Ignition 1 Voltage

--

P0031, P0037

--

--

HO2S 1 Heater Control

P0031

P0031

P0032

P0031

HO2S 2 Heater Control

P0037

P0037

P0038

P0037, P0141

PCM HO2S 1 Ground

--

P0031

--

--

PCM HO2S 2 Ground

--

P0037

--

--

Circuit Description

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:

    • A signal circuit
    • A low reference circuit
    • An ignition 1 voltage circuit
    • A heater control circuit
    • An oxygen sensor dedicated control module ground circuit

Conditions for Running the DTC

    • DTCs P0037 and P0038 are not set.
    • The battery is between 10.5-16 volts.
    • The engine has been operating for greater than 10 seconds.
    • The DTC runs once per ignition cycle when the above conditions are met.

Conditions for Setting the DTC

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

Action Taken When the DTC Sets

DTC P0141 is a Type B DTC.

Conditions for Clearing the MIL/DTC

DTC P0141 is a Type B DTC.

Diagnostic Aids

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.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

    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.

Circuit/System Testing

  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.
  3. 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.
  4. Ignition OFF, connect the HO2S circuits together with four 10 amp fused jumper wires.
  5. Important: The following test must be performed with both the HO2S sensor and the control module connected and operating normally.

  6. Ignition ON, verify a test lamp illuminates between the control circuit terminal 1 and ground.
  7. 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.

  8. 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.
  9. If the test lamp is always ON, test for an open/high resistance in the heater control circuit.
  10. If all circuits test normal, replace the PCM.

Component Testing

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

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Air Intake System Description
    •  Control Module References for control module replacement, setup, and programming