how to troubleshoot my Honda Civic 10th Generation (2016-2021) that has a P0138 code

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the negative battery terminal for safety.

2. Inspect and Repair Wiring

• Remove the engine cover if necessary to gain access to the harness.
• Visually inspect the wiring and connectors of the upstream oxygen sensor.
• If damaged, repair or replace any faulty wiring or connectors.

3. Replace the Upstream Oxygen Sensor

• Locate the upstream oxygen sensor (typically near the exhaust manifold).
• Use an O2 sensor socket to remove the old sensor by turning it counter-clockwise.
• Apply anti-seize compound to the threads of the new sensor (if recommended).
• Install the new oxygen sensor by threading it in clockwise and tightening it to the manufacturer’s specifications (typically 30-40 ft-lbs).
• Reconnect the electrical connector to the oxygen sensor.

4. Clear the Error Codes

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

5. Test Drive

• Start the engine and allow it to idle for a few minutes.
• Take the vehicle for a test drive, monitoring for any check engine light illumination.