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 control module monitors the current draw of the heater to determine if a failure is present.

The HO2S utilizes the following circuits:

The ECM detects that the HO2S 2 heater resistance is less than 10 ohms or greater than 30 ohms

DTC P0141 is a Type B DTC.

DTC P0141 is a Type B DTC.

Schematic Reference

Engine Controls Schematics

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.

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.

1. Ignition OFF, disconnect the harness connector at the appropriate H02S.
2. Ignition ON, verify that a test lamp illuminates between the ignition 1 voltage circuit terminal 2 and ground.

Important: The ignition 1 voltage circuit supplies voltage to other components. Make sure you test all circuits for a short to ground or test all components for being shorted that share the ignition 1 voltage circuit.

⇒	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 a test lamp between the control circuit terminal 3 and 12 volts. The test lamp should not illuminate.

⇒	If test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM.

4. Engine running, verify the test lamp illuminates or flashes.

⇒	If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

5. If all circuits test normal, test or replace the H02S sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.