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 negative battery terminal to avoid electrical issues.

2. Inspect and Replace Oxygen Sensors

1. Locate the Oxygen Sensors:

   • Identify the upstream and downstream oxygen sensors on the exhaust system.

2. Remove the Oxygen Sensors:

   • Use an oxygen sensor socket to carefully unscrew the sensors from their connections.

3. Inspect the Sensors:

   • Check the sensors for any signs of damage or contamination. Replace if necessary.

4. Install New Sensors:

   • Apply anti-seize compound to the threads of the new sensors.
   • Screw in the new sensors and tighten to the manufacturer's specifications (usually around 30-40 lb-ft).

5. Reconnect Battery Terminal:

   • Reconnect the negative battery terminal securely.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Check the Catalytic Converter:

   • Inspect for any visible damage or excessive heat discoloration.

2. Remove the Catalytic Converter:

   • Loosen the bolts connecting the catalytic converter to the exhaust system using a socket set.
   • Carefully detach the catalytic converter from the vehicle.

3. Install New Catalytic Converter:

   • Position the new catalytic converter in place and align it with the exhaust system.
   • Secure it using the original or new bolts, tightening to the specified torque (usually around 30-40 lb-ft).

4. Recheck Exhaust System:

   • Inspect all connections for tightness and ensure there are no leaks.