P0138

Tests 1 - 3:

Tests 4 - 7:

SYMPTOM
P0138 - 1/2 O2 SENSOR SHORTED TO VOLTAGE

WHEN MONITORED
With the engine running for more than 2 minutes and coolant temperature above 76 °C (170 °F).

SET CONDITION
The Downstream Oxygen Sensor Signal voltage is above 1.2 volts.

POSSIBLE CAUSES
- 1/2 O2 sensor signal circuit short to voltage
- 1/2 O2 sensor harness intermittent shorted to voltage
- 1/2 O2 sensor connector observable defect (A)
- 1/2 O2 sensor connector observable defect (B)
- 1/2 O2 sensor harness observable defect
- 1/2 O2 sensor defective