how do I fix the P0138 code on my Honda Civic 9th Generation (2012-2015)?

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical short circuits.
• Allow the engine to cool down.

2. Remove the Upstream O2 Sensor

• Locate the upstream O2 sensor, which is usually found on the exhaust manifold or the front of the catalytic converter.
• Use a wrench or O2 sensor socket to carefully unscrew and remove the O2 sensor from the exhaust system.
• Disconnect the electrical connector from the O2 sensor.

3. Inspect and Clean Wiring

• Inspect the wiring harness for any signs of wear, fraying, or damage.
• If damaged, repair or replace the wiring as necessary.
• Clean the electrical connectors with electrical contact cleaner to ensure a good connection.

4. Install New O2 Sensor

• Apply anti-seize compound to the threads of the new O2 sensor (if not pre-applied).
• Screw in the new O2 sensor by hand to avoid cross-threading, then tighten it with a wrench to the manufacturer's specifications (usually around 30-40 lb-ft).
• Reconnect the electrical connector securely.

5. Reconnect Battery and Test

• Reconnect the negative battery terminal.
• Start the engine and allow it to reach operating temperature.
• Use the OBD-II scanner to clear the P0138 code and check for any reoccurrence.