how to fix P0138 code on my Toyota Corolla E140 (2006-2013)

Learn how to diagnose and fix P0138 high voltage issue in the oxygen sensor of a 2006-2013 Toyota Corolla E140. Step-by-step guide included.

Solution

1. Preparation

• Gather all necessary tools and parts.
• Ensure the vehicle is parked on a level surface, and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensor

• Tools Required: O2 sensor socket, ratchet, torque wrench, multimeter, safety goggles.
• Sub-steps:
  1. Locate the downstream oxygen sensor (typically found on the exhaust pipe after the catalytic converter).
  2. Disconnect the electrical connector from the oxygen sensor.
  3. Use the O2 sensor socket and ratchet to remove the old sensor from the exhaust pipe.
  4. Inspect the threads of the sensor hole for damages; clean if necessary.
  5. Install the new oxygen sensor by hand-tightening it first, then use the torque wrench to tighten it to the manufacturer's specifications (typically around 30 lb-ft).
  6. Reconnect the electrical connector securely.

3. Clear Codes and Test Drive

• Reconnect the negative battery terminal.
• Use an OBD-II scanner to clear the P0138 code.
• Start the engine and allow it to reach operating temperature.
• Perform a test drive to monitor engine performance and check for the reoccurrence of the check engine light.