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 an ignition voltage circuit through a fuse. With the engine running, ground is provided to the heater by the HO2S heater low control circuit, through a low side driver within the powertrain control module (PCM). The PCM uses pulse width modulation (PWM) to control the HO2S heater operation to maintain a specific HO2S operating temperature range.

The PCM determines the temperature by measuring the current flow through the heater and calculating the resistance. Based on the resistance, the PCM can predict the sensor temperature. The HO2S uses pulse width modulation (PWM) to control the heater operation. The PCM calculates the heater resistance on a cold start. This diagnostic will only run once per ignition cycle. If the PCM detects that the heater calculated resistance is not within the expected range, DTC P0053 sets for HO2S 1, or DTC P0054 sets for HO2S 2.

DTC P0053 and P0054 are Type B DTCs.

DTC P0053 and P0054 are Type B DTCs.

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

Scan Tool Data List

1. Allow the engine to reach operating temperature.
2. Engine running, verify the appropriate scan tool HO2S Heater parameter is varying between 0.5-2 amp.

Important:  You must perform the Circuit/System Verification before proceeding with 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 appropriate HO2S heater voltage supply circuit terminal D and ground.

⇒	If the test lamp does not illuminate, test the HO2S heater voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal and the HO2S heater voltage supply circuit fuse is open, test all components connected to the fuse and replace as necessary.

3. Ignition ON, verify that a test lamp does not illuminate between the appropriate HO2S heater low control circuit terminal C and the HO2S heater voltage supply circuit terminal D.

⇒	If the lamp illuminates, test the HO2S heater low control circuit for a short to ground. If the circuit tests normal, replace the PCM.

4. Engine running, leave the test lamp connected from the previous step. The lamp should flash or be ON steady.

⇒	If the test lamp is not on steady or flashing, test the HO2S heater low control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the PCM.

Important: 

•	The output driver should detect a short to voltage and turn OFF. If a resistance fault is present the driver will remain ON and the scan tool will display more than 0.0A. Less than 10 ohms of resistance may set a DTC.

•	Performing this test may set additional DTCs.

5. Ignition OFF, install a 30A fused jumper wire between the appropriate HO2S heater low control circuit terminal C and the HO2S heater voltage supply circuit terminal D.
6. Engine running, verify the appropriate scan tool Heater parameter is less than 0.1A.

⇒	If more than the specified range, test the HO2S heater voltage supply and HO2S heater low control circuits for more than 1 ohm of resistance. If the circuits test normal, replace the PCM.

7. If the PCM and all circuits test normal, replace the appropriate HO2S.

Notice: Refer to Heated Oxygen Sensor Resistance Learn Reset Notice in the Preface section.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.