how to fix P0138 code in Honda Civic 9th Generation (2012-2015)

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.
• Ensure the engine is cool before starting work.

2. Remove the Downstream O2 Sensor

• Tools Required: Oxygen sensor socket, ratchet, and extension.
• Locate the downstream oxygen sensor (after the catalytic converter).
• Use the oxygen sensor socket to carefully unscrew the sensor from the exhaust pipe.
• Disconnect the electrical connector from the sensor.

3. Inspect and Replace the Oxygen Sensor

• Visually inspect the old sensor for signs of damage or excessive wear.
• If the sensor appears faulty, install the new downstream O2 sensor:
  • Apply anti-seize compound on the threads of the new sensor (if not pre-applied).
  • Screw the new sensor into place by hand and then tighten it with the oxygen sensor socket to the manufacturer’s specified torque (usually around 30 lb-ft).
• Reconnect the electrical connector securely.

4. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0138 code from the vehicle’s computer.

5. Test Drive and Monitor

• Start the engine and let it idle for a few minutes.
• Take the vehicle for a test drive under various conditions to allow the O2 sensor to begin functioning and be monitored by the ECU.