how to fix P0420 code on Honda Civic 11th Generation (2022-Present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface, and set the parking brake.
• Disconnect the battery to avoid electrical issues while working on the vehicle.

2. Inspect and Replace Oxygen Sensors

1. Locate the upstream and downstream oxygen sensors in the exhaust system.
2. Use an O2 sensor socket to remove the upstream oxygen sensor.
3. Install the new upstream oxygen sensor and tighten to the manufacturer's specifications (typically around 30 Nm).
4. Repeat the process for the downstream oxygen sensor if found faulty.

3. Inspect and Replace the Catalytic Converter

1. Remove any heat shields or covers obstructing access to the catalytic converter.
2. Disconnect the exhaust pipes from the catalytic converter using a socket set.
3. Remove the old catalytic converter by unbolting it from the exhaust manifold and the mid-pipe.
4. Install the new catalytic converter, ensuring proper alignment, and tighten bolts to manufacturer specifications (typically around 35 Nm).
5. Reattach any heat shields or covers removed in the process.

4. Reconnect Battery and Clear Codes

1. Reconnect the vehicle's battery.
2. Use the OBD-II scanner to clear the P0420 code and any other stored codes.
3. Start the engine and let it idle for a few minutes.