why does my Toyota RAV4 XA50 (2019-2024) show a check engine light with code P0138

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative terminal of the battery to ensure safety.
• Allow the vehicle to cool down if it has been running.

2. Inspect and Repair Wiring

• Tools Required: Wire stripper/crimper, electrical tape
• Inspect the wiring harness connected to the oxygen sensor for any visible damage.
• If damage is found, repair or replace the affected wires.
• Ensure all connections are secure and free of corrosion.

3. Replace Oxygen Sensor

• Tools Required: Oxygen sensor socket, ratchet, torque wrench
• Locate the oxygen sensor (usually located upstream of the catalytic converter).
• Use the oxygen sensor socket to unscrew and remove the old sensor.
• Apply anti-seize compound to the threads of the new sensor.
• Install the new oxygen sensor and tighten it to the manufacturer’s specified torque (usually around 30 lb-ft).

4. Clear Codes and Test

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the check engine codes.
• Start the engine and allow it to reach operating temperature.