how to fix P0420 code on my Honda Civic 10th Generation (2016-2021)?

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the vehicle battery to prevent electrical shorts.
• Safety glasses and gloves should be worn during the repair.

2. Inspect and Replace Oxygen Sensors

1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
2. Using a socket wrench, remove the oxygen sensors from their respective locations.
3. Inspect the sensors for damage or contamination; replace if necessary.
   • Tools Required: Oxygen sensor socket, torque wrench
   • Safety Warning: Ensure the exhaust system is cool before touching any components.

3. Replace Catalytic Converter (if necessary)

1. If the catalytic converter is determined to be faulty, support the vehicle securely on jack stands.
2. Remove any heat shields covering the catalytic converter using a socket set.
3. Disconnect the exhaust pipes from the catalytic converter.
4. Remove the catalytic converter from its mounting brackets.
5. Install the new catalytic converter, ensuring it is properly aligned.
6. Reconnect the exhaust pipes and torque them to manufacturer specifications.
   • Tools Required: Socket set, torque wrench