how to fix P0138 oxygen sensor high voltage code in Volvo XC60 Second Generation (2018-2024)

Learn how to diagnose and fix P0138 oxygen sensor high voltage issue in Volvo XC60. Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool if it has been running.

2. Inspect and Repair Wiring

• Tools Required: Multimeter, wire brush, electrical contact cleaner
• Check all wiring and connectors for wear or corrosion.
• Clean any corroded connectors with electrical contact cleaner.
• Repair or replace damaged wiring or connectors as necessary.

3. Replace Oxygen Sensor

• Tools Required: O2 sensor socket, wrench set, torque wrench
• Locate the oxygen sensor (usually found in the exhaust system, upstream or downstream of the catalytic converter).
• Disconnect the electrical connector from the oxygen sensor.
• Use an O2 sensor socket to unscrew the old sensor from its mounting.
• Apply anti-seize compound to the threads of the new oxygen sensor.
• Install the new sensor and tighten it to the manufacturer’s specified torque (typically around 30 lb-ft).
• Reconnect the electrical connector.

4. Clear Codes and Test Drive

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0138 code.
• Start the vehicle and allow it to reach operating temperature.
• Take the vehicle for a test drive to ensure the check engine light does not reappear and monitor fuel trim values.