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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety during repairs.

Tools Required:

• OBD-II scanner
• Socket set
• Torque wrench
• Multimeter
• Safety glasses
• Gloves

2. Inspect and Replace Oxygen Sensors

1. Locate the upstream and downstream oxygen sensors.
2. Disconnect the electrical connectors from both sensors.
3. Using a socket, remove both oxygen sensors from the exhaust system.
4. Install new oxygen sensors, ensuring they are properly torqued according to specifications (typically around 30 Nm or 22 lb-ft).
5. Reconnect the electrical connectors to the sensors.

3. Inspect and Replace Catalytic Converter (if necessary)

1. If the catalytic converter shows signs of damage or blockage, proceed to replace it.
2. Remove any heat shields or components obstructing access to the catalytic converter.
3. Unbolt the catalytic converter from the exhaust manifold and the exhaust pipe.
4. Install the new catalytic converter, ensuring proper alignment and torque specifications are followed (typically around 40 Nm or 30 lb-ft).
5. Reinstall any heat shields or components removed earlier.

4. Clear Codes and Test Drive

1. Reconnect the vehicle battery.
2. Use the OBD-II scanner to clear any stored trouble codes.
3. Start the engine and allow it to reach operating temperature.
4. Conduct a test drive to ensure the vehicle operates normally and monitor for any reoccurring codes.