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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the battery to prevent any electrical short circuits.
• Raise the vehicle on jack stands for better access to the exhaust system.

2. Inspect and Replace Oxygen Sensors

1. Remove the upstream oxygen sensor (pre-catalytic converter):
   • Use an oxygen sensor socket to unscrew the sensor.
   • Disconnect the wiring harness.
2. Install the new upstream oxygen sensor:
   • Apply anti-seize compound on the threads of the new sensor.
   • Torque to manufacturer specifications (typically around 30 lb-ft).
3. Remove the downstream oxygen sensor (post-catalytic converter) using the same method.
4. Install the new downstream oxygen sensor and torque accordingly.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Remove the catalytic converter:
   • Loosen and remove the bolts or clamps securing it to the exhaust system.
   • Carefully detach the converter from the exhaust pipe.
2. Install the new catalytic converter:
   • Align the converter with the exhaust system.
   • Secure it using new gaskets and bolts, torqued to manufacturer specifications.
3. Reattach any heat shields or brackets that were removed during the process.

4. Reconnect Battery and Clear Codes

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