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 a ground is provided to the heater by the HO2S heater low control circuit, through a low side driver within the engine control module (ECM). The ECM uses pulse width modulation (PWM) to control the HO2S heater operation to maintain a specific HO2S operating temperature range.

P0053 and P0059

P0053 or P0059

The ECM detects that the HO2S heater calculated resistance is not between 1.3 and 7.5 ohms at engine start-up for 1 second.

DTC P0053 and P0059 are Type B DTCs.

DTC P0053, and P0059 are Type B DTCs.

When using a high impedance, low current draw, test lamp to load the heater circuit, the test lamp flash may be dim. The scan tool Heater Command parameter may indicate 7 percent and the Heater parameter may indicate 0 amps. This is a normal condition.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

DTC Type Reference

Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

1. Allow the engine to reach operating temperature.
2. Engine running, verify the appropriate scan tool HO2S Heater parameter is varying between approximately 0.5-2 amp.
3. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Note:  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 harness connector terminal 1 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 voltage supply circuit harness connector terminal 1 and the appropriate HO2S heater low control circuit harness connector terminal 2.

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

4. Ignition ON, 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 ECM.

Note: 

•	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 0.0 amp. Less than 10 ohms 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 voltage supply circuit harness connector terminal 1 and the appropriate HO2S heater low control circuit harness connector terminal 2.
6. Engine running, verify the appropriate scan tool HO2S Heater parameter is less than 0.1 amp.
7. If more than the specified range, test the HO2S heater voltage supply and HO2S heater low control circuits for more than 1 ohm.

•	ECM harness connector X1 terminal 96 and the HO2S B1S1 low reference harness connector terminal 2

•	ECM harness connector X1 terminal 72 and the HO2S B1S1 low reference harness connector terminal 2

•	HO2S heater supply voltage circuit harness connector terminal 1 and the under bonnet electrical centre (UBEC) fuse 33.

8. If the ECM and all circuits test normal, replace the appropriate HO2S.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.