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 the engine is cool.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

1. Locate the oxygen sensors: The upstream sensor is usually before the catalytic converter, and the downstream sensor is after it.
2. Disconnect the connectors: Carefully unplug the electrical connectors from both the upstream and downstream oxygen sensors.
3. Remove the sensors: Use an oxygen sensor socket or wrench to unscrew the sensors from the exhaust manifold and catalytic converter.
4. Install new sensors: Apply anti-seize compound on the threads of the new sensors and install them securely.
5. Reconnect the electrical connectors: Ensure that the connectors are firmly attached.

3. Inspect and Replace the Catalytic Converter (if necessary)

1. Examine the catalytic converter: Look for signs of damage, such as dents or rust.
2. Remove the catalytic converter: Use a socket set to unbolt the converter from the exhaust pipes.
3. Install the new catalytic converter: Place the new converter into position and secure it with bolts to the exhaust pipes, ensuring proper alignment.
4. Torque bolts to specifications: Refer to the service manual for the specific torque settings.
5. Reconnect any removed components: Ensure all exhaust components are properly fitted back together.

4. Reconnect Battery and Test

1. Reconnect the battery: Ensure all connections are secure.
2. Start the engine: Allow it to run for a few minutes to check for leaks and ensure the check engine light is off.
3. Take the vehicle for a test drive: Monitor performance and verify that the check engine light does not reappear.