P0138 O2 Sensor Circuit High Voltage Bank 1 Sensor 2

Definition: The P0138 code indicates that the oxygen sensor located in bank 1, sensor 2 is reporting a high voltage condition. This typically means that the sensor is detecting a rich air-fuel mixture.

p0138: O2 Sensor Circuit High Voltage Bank 1 Sensor 2

Typical Severity: Moderate

Common Causes

p0138: O2 Sensor Circuit High Voltage Bank 1 Sensor 2

Common causes:

• Faulty oxygen sensor
• Short to voltage in the signal circuit
• Open or short in the ground circuit
• Poor electrical connection in the oxygen sensor circuit
• Fuel pressure too high causing a rich condition

 

Common Misdiagnosis

OBD2 Code: P0138

Description: O2 Sensor Circuit High Voltage Bank 1 Sensor 2

Common Misdiagnosis: Replacing the oxygen sensor without checking for exhaust leaks or issues with the wiring harness and connectors.

 

Common Diagnostic Steps

OBD2 Code: P0138

Description: O2 Sensor Circuit High Voltage Bank 1 Sensor 2

Common Diagnostic Steps:

• Check the oxygen sensor wiring and connectors for damage or corrosion.
• Inspect the exhaust system for leaks that may affect sensor readings.
• Test the voltage output of the oxygen sensor using a multimeter.
• Verify proper operation of the engine control module (ECM) related to sensor inputs.
• Examine fuel pressure and injector performance for irregularities.
• Replace the oxygen sensor if it is found to be faulty after testing.