Spark

DTC P0031, P0032, P0037, or P0038

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 minimises the time required for the sensor to reach operating temperature. Voltage is provided to the heater by the ignition 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 utilises the following circuits:

P0031, P0032, P0037, or P0038

P0135 or P0141

P0031 or P0037

The ECM detects a short circuit to ground or an open circuit on the HO2S heater control circuit.

P0032 or P0038

The ECM detects a short circuit to battery on the HO2S heater control circuit.

P0135 or P0141

The ECM detects that the filtered HO2S heater current is less than the predetermined values.

DTC P0031, P0032, P0037, P0038, P0135, and P0141 are Type E DTCs.

DTC P0031, P0032, P0037, P0038, P0135, and P0141 are Type E DTCs.

Schematic Reference

Engine Controls Schematics : Siemens ECM - LPG with LCP → Siemens ECM - Gas without FX3 or LCP → Delphi ECM - FX3

Connector End View Reference

Component Connector End Views

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information.

1. Engine idling, observe the HO2S heater control circuit test status parameters. Each of the HO2S heater control circuit test status parameters should display OK or Not Run.
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.

1. Ignition OFF, disconnect the harness connector at the appropriate heated oxygen sensor (HO2S).

•	B52A Heated Oxygen Sensor 1 (HO2S1)

•	B52B Heated Oxygen Sensor 2 (HO2S2)

2. Ignition ON, verify that a test lamp illuminates between the ignition circuit of the appropriate HO2S and ground.

•	Ignition circuit terminal 4 of the B52A HO2S1 and ground

•	Ignition circuit terminal 4 of the B52B HO2S2 and ground

⇒	If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and its 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 control circuit and the ignition circuit of the appropriate HO2S.

•	Control circuit terminal 2 and ignition circuit terminal 4 of the B52A HO2S1

•	Control circuit terminal 2 and ignition circuit terminal 4 of the B52B HO2S2

⇒	If the test lamp illuminates, test the control circuit for a short to ground. If the circuit tests normal, replace the K20 engine control module (ECM).

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 control circuit of the appropriate HO2S for a short circuit to voltage or an open/high resistance. If the circuit tests normal, replace the K20 engine control module (ECM).

5. If all circuits test normal, replace the appropriate HO2S.

1. Ignition OFF, disconnect the harness connector at the HO2S.
2. Test for 3-23 Ω between the control terminal and the ignition terminal of the appropriate HO2S.

•	Control terminal 2 and ignition terminal 4 of the B52A HO2S1

•	Control terminal 2 and ignition terminal 4 of the B52B HO2S2

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

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.