P0031

P0031 - O2 SENSOR 1/1 HEATER CIRCUIT LOW





For a complete wiring diagram Consult Diagrams/Electrical

- When Monitored:
With the ignition on and the Oxygen Sensor Heater command on.

- Set Condition:
The ECM detects that the (K99) O2 1/1 Heater Control circuit is shorted to ground for 2.0 seconds.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.Initial Inspection and Diagnostic Overview

Diagnostic Test

1. DTC IS ACTIVE
Ignition on, engine not running.
With the scan tool, Clear DTCs in the Engine Control Module (ECM).
Start the engine and allow it to reach normal operating temperature.
With the scan tool, select View DTCs.
Is the status Active for this DTC?

Yes

- Go To 2

No

- Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure.Intermittent Condition

2. (K99) O2 1/1 HEATER CONTROL CIRCUIT SHORTED TO GROUND




Turn the ignition off.
Disconnect the Oxygen Sensor harness connector.
Disconnect the Engine Control Module (ECM) harness connector.
Measure the resistance between ground and the (K99) O2 1/1 Heater Control circuit in the Oxygen Sensor harness connector.
Is the resistance below 1000 ohms?

Yes

- Repair the (K99) O2 1/1 Heater Control circuit for a short to ground.
- Perform the ECM Verification Test Ver. 1. Verification Tests

No

- Go to 3

3. (K99) O2 1/1 HEATER CONTROL CIRCUIT OPEN OR HIGH RESISTANCE




Measure the resistance of the (K99) O2 1/1 Heater Control circuit between the Oxygen Sensor harness connector and the Engine Control Module (ECM) harness connector.
Is the resistance below 10.0 ohms?

Yes

- Go to 4

No

- Repair the (K99) O2 1/1 Heater Control circuit for an open circuit or high resistance.
- Perform the ECM Verification Test Ver. 1. Verification Tests

4. OXYGEN SENSOR
Connect the Engine Control Module (ECM) harness connector.
Replace the Oxygen Sensor.
Turn the ignition on.
With the scan tool, Clear DTCs.
Start the engine and allow it to reach normal operating temperature.
With the scan tool, select View DTCs.
Is the status Active for this DTC?

Yes

- Go to 5

No

- Test Complete.
- Perform the ECM Verification Test Ver. 1. Verification Tests

5. ENGINE CONTROL MODULE (ECM)
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Oxygen Sensor and the Engine Control Module (ECM).
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals.
Search for any Technical Service Bulletins that may apply.
Were any problems found?

Yes

- Repair as necessary.
- Perform the ECM Verification Test Ver. 1. Verification Tests

No

- Replace the Engine Control Module (ECM).
- Perform the ECM Verification Test Ver. 1. Verification Tests