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

Solution

1. Preparation

• Gather tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Replace O2 Sensors

• Tools Required: O2 sensor socket, wrench set, torque wrench.
• Remove the pre-catalytic O2 sensor:
  • Locate the sensor on the exhaust manifold.
  • Use the O2 sensor socket to unscrew it, counterclockwise.
• Install the new O2 sensor:
  • Apply anti-seize compound to the threads (if recommended).
  • Torque the sensor to the manufacturer's specification (usually around 30 lb-ft).
• Repeat the process for the post-catalytic O2 sensor if needed.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, jack and jack stands, exhaust hanger removal tool.
• Lift the vehicle and secure it with jack stands.
• Remove the exhaust hangers to detach the catalytic converter from the exhaust system.
• Unbolt the catalytic converter from the exhaust manifold and mid-pipe.
• Install the new catalytic converter:
  • Ensure proper alignment with exhaust flanges.
  • Torque bolts to manufacturer specifications (typically around 22 lb-ft).
• Reattach exhaust hangers.

4. Reconnect Battery and Clear Codes

• Reconnect the battery terminals.
• Use the OBD-II scanner to clear the P0420 code.