how to fix P0420 code in my Honda Accord 9th Generation (2013-2017)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety during repairs.
• Allow the exhaust system to cool before beginning work.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench
• Remove the upstream oxygen sensor by using the O2 sensor socket.
• Inspect the sensor for damage or contamination.
• If faulty, replace it with a new one and torque to manufacturer specifications (typically around 30 ft-lb).
• Repeat the process for the downstream oxygen sensor if necessary.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, torque wrench, cutting tool if necessary
• Remove the exhaust pipes connected to the catalytic converter.
• Inspect the catalytic converter for physical damage, rattling sound, or blockage.
• If defective, unbolt the old catalytic converter and replace it with a new one.
• Ensure all gaskets are replaced and torque all bolts to manufacturer specifications.

4. Clear Error Codes

• Reconnect the battery.
• Use an OBD-II scanner to clear the P0420 code from the vehicle's computer system.

5. Test Drive

• Conduct a test drive to ensure the vehicle operates normally and the check engine light does not reappear.