P0031
P0031-O2 SENSOR 1/1 HEATER CIRCUIT LOWP0031-O2 Sensor 1/1 Heater Circuit Low:
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.
POSSIBLE CAUSES
- (K99) O2 sensor 1/1 heater control circuit shorted to ground
- O2 sensor
- PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.
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.
With the scan tool, monitor 1/1 O2 Sensor voltage for at least 2 minutes.
Q: Does the O2 Sensor voltage stay above 4.5 volts?
YES: Go To 2
NO: Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition
Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
2. O2 HEATER ELEMENT
Turn the ignition off.
NOTE: Allow the O2 Sensor to cool down to room temperature.
Disconnect the 1/1 O2 Sensor harness connector.
Measure the resistance across the O2 Sensor Heater element, between the Heater Control terminal and the Heater ground terminal at the component.
NOTE: O2 Heater Element resistance values should be measured at 70° F (21.1° C). The resistance value will vary with different temperature values.
Q: Is the O2 Sensor Heater Element resistance between 2.0 and 30.0 ohms?
YES: Go To 3
NO: Replace the O2 Sensor. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
3. 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.
Using a 12-volt test light connected to ground, probe the (K99) O2 1/1 Heater Control circuit in the O2 Sensor harness connector.
Q: Does the test light illuminate brightly and flash on and off during the actuation?
YES: Replace the O2 Sensor. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 4
4. (K99) O2 1/1 HEATER CONTROL CIRCUIT SHORTED TO GROUND
Turn the ignition off.
Disconnect the PCM harness connectors.
Measure the resistance between ground and the (K99) O2 1/1 Heater Control circuit in the O2 Sensor harness connector.
Q: Is the resistance below 5.0 ohms?
YES: Repair the short to ground in the (K99) O2 1/1 Heater Control circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 5
5. 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.
Q: Were there any problems found?
YES: Repair as necessary. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Replace and program the Powertrain Control Module. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test