P0038
P0038-O2 SENSOR 1/2 HEATER CIRCUIT HIGHP0038-O2 Sensor 1/2 Heater Circuit High:
WHEN MONITORED:
Battery voltage above 10.6 volts, ASD is powered up, and O2 heater is off.
SET CONDITION:
Desired state does not equal Actual state. One Trip Fault. Three good trips to turn off the MIL.
POSSIBLE CAUSES
- (K299) O2 1/2 heater control circuit open
- (Z42) O2 1/2 heater ground circuit open
- (K299) O2 sensor 1/2 heater control circuit shorted to battery voltage
- O2 sensor
- PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.
Diagnostic Test
1. ACTIVE DTC
Ignition on, engine not running.
With a scan tool, read DTC's.
Q: Is the DTC active at this time?
YES: Go To 2
NO: Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Component Tests and General Diagnostics
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 1/2 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. (K299) O2 1/2 HEATER CONTROL CIRCUIT
Ignition on, engine not running.
With a scan tool, actuate the O2 1/2 Heater Test with the O2 Sensor harness connector still disconnected.
Using a 12-volt test light connected to ground, probe the (K299) O2 1/2 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: Go To 4
NO: Go To 5
4. (Z42) O2 HEATER GROUND CIRCUIT OPEN
Turn the ignition off.
Measure the resistance between an engine ground and the (Z42) O2 1/2 Heater ground circuit in the O2 Sensor harness connector.
Q: Is the resistance below 5.0 ohms?
YES: Replace the O2 Sensor. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Repair the open in the (Z42) O2 1/2 Heater ground circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
5. (K299) O2 1/2 HEATER CONTROL CIRCUIT SHORTED TO BATTERY VOLTAGE
Turn the ignition off.
Disconnect the C3 PCM harness connector.
Ignition on, engine not running.
Using a 12-volt test light connect to ground, probe the (K299) O2 1/2 Heater Control circuit in the O2 Sensor harness connector.
Q: Does the test light illuminate brightly?
YES: Repair the short to battery voltage in the (K299) O2 1/2 Heater Control circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 6
6. (K299) O2 1/2 HEATER CONTROL CIRCUIT OPEN
Turn the ignition off.
CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.
Measure the resistance of the (K299) O2 1/2 Heater Control circuit from the O2 Sensor harness connector to the appropriate terminal of special tool #8815.
Q: Is the resistance below 5.0 ohms?
YES: Go To 7
NO: Repair the open in the (K299) O2 1/2 Heater Control circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
7. 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