how to fix P0138 oxygen sensor code in my Volkswagen Passat B8 (2015-2022)

Learn how to diagnose and fix P0138 oxygen sensor code in Volkswagen Passat B8. Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the vehicle's battery to ensure safety during repairs.
• Raise the vehicle using a jack and secure it on jack stands if needed.

2. Remove the Oxygen Sensor

• Locate the upstream oxygen sensor (usually found in the exhaust manifold or pipe).
• Disconnect the electrical connector from the sensor.
• Use an oxygen sensor socket or a wrench to carefully unscrew the sensor from the exhaust.
• Tools Required: Oxygen sensor socket, ratchet, wrench.

3. Inspect and Clean

• Inspect the threads of the sensor and the mounting hole for carbon buildup or damage.
• Clean any deposits from the mounting area using a wire brush or a suitable cleaner.
• Tools Required: Wire brush, cleaner.

4. Install New Oxygen Sensor

• Apply anti-seize compound to the threads of the new oxygen sensor (if not pre-applied).
• Screw the new sensor into the exhaust pipe and tighten it to the manufacturer’s specifications (usually around 30 lb-ft).
• Reconnect the electrical connector securely.
• Parts Required: New oxygen sensor.

5. Reconnect Battery and Test

• Reconnect the vehicle’s battery.
• Start the engine and let it idle for a few minutes to ensure the sensor is operating.
• Check for any exhaust leaks around the sensor.