how to fix the P0138 code in my Tesla Model S Plaid/Refresh (2021-present)

Learn how to diagnose and fix P0138 high voltage from the oxygen sensor in Tesla Model S Plaid. Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather tools and parts: OBD-II scanner, multimeter, socket set, and replacement oxygen sensor (if necessary).
• Ensure the vehicle is parked on a flat surface with the parking brake engaged.

2. Disconnect Battery

• Disconnect the negative terminal of the 12V battery to prevent electrical shorts.
• Wait at least 5 minutes to allow systems to discharge.

3. Remove the Oxygen Sensor

• Locate the upstream oxygen sensor on the exhaust manifold.
• Use a socket wrench to remove the sensor, turning it counterclockwise.
• Carefully unplug the electrical connector from the sensor.

4. Inspect and Replace

• Inspect the threads of the oxygen sensor port for damage or buildup. Clean if necessary.
• If the sensor was confirmed faulty (high voltage output), install the new oxygen sensor:
  • Apply anti-seize compound on the threads of the new sensor.
  • Thread the new sensor into the port and tighten it to the manufacturer’s specified torque (usually around 30 Nm or 22 lb-ft).

5. Reconnect Components

• Plug the electrical connector back into the new oxygen sensor.
• Reconnect the negative terminal of the battery.

6. Clear Codes and Test

• Use the OBD-II scanner to clear the P0138 code.
• Start the vehicle and let it reach operating temperature.
• Conduct a test drive to monitor engine performance and check for any reoccurrence of the code.