P0031

P0031-O2 SENSOR 1/1 HEATER CIRCUIT LOW





For a complete wiring diagram Consult Diagrams/Electrical.

- When Monitored:
Battery voltage above 10.6 volts, ASD is powered up, and O2 heater is powered.

- Set Condition:
Desired state does not match Actual state. One Trip Fault. Three good trips to turn off the MIL.





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

Diagnostic Test

1. O2 SENSOR HEATER OPERATION
Turn the ignition off.

NOTE: Wait a minimum of 8 minutes to allow the O2 Sensor to cool down before continuing the test. Allow the O2 Sensor voltage to stabilize at 5.0 volts.

Ignition on, engine not running.
With a scan tool, actuate the O2 Heater Test.

NOTE: The DTC needs to be cleared before actuating the Heater Test, if the DTC is not cleared, the Heater Test may not be allowed to actuate.

With the scan tool, monitor 1/1 O2 Sensor voltage for at least 2 minutes.
Does the O2 Sensor voltage stay above 4.5 volts?

Yes

- Go to 2

No

- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Checking for an Intermittent DTC.

2. O2 SENSOR




Ignition on, engine not running.
With a scan tool, actuate the O2 1/1 Heater Test with the O2 Sensor harness connector still disconnected.

NOTE: The DTC needs to be cleared before actuating the Heater Test, if the DTC is not cleared, the Heater Test may not be allowed to actuate.

Using a 12-volt test light connected to 12-volts, probe the (K99) O2 1/1 Heater Control circuit in the O2 Sensor harness connector.
Does the test light illuminate brightly and flash on and off during the actuation?

Yes

- Replace the O2 Sensor.
- Perform the PCM Verification Test.PCM Verification Test

No

- Go to 3

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




Turn the ignition off.
Disconnect the C2 PCM harness connector.
Measure the resistance between ground and the (K99) O2 1/1 Heater Control circuit in the O2 Sensor harness connector.
Is the resistance below 5.0 ohms?

Yes

- Repair the short to ground in the (K99) O2 1/1 Heater Control circuit.
- Perform the PCM Verification Test.PCM Verification Test

No

- Go To 4

4. PCM
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.

Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.
Were there any problems found?

Yes

- Repair as necessary.
- Perform the PCM Verification Test.PCM Verification Test

No

- Replace and program the Powertrain Control Module.
- Perform the PCM Verification Test.PCM Verification Test