how to fix P0420 code on my 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 battery to avoid electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Remove the upstream oxygen sensor (before the catalytic converter) by using the O2 sensor socket.
  • Sub-step: Inspect the sensor for contamination or damage. Replace if necessary.
• Reinstall the new oxygen sensor and torque it to manufacturer specifications (usually around 30 lb-ft).
• Repeat the process for the downstream oxygen sensor (after the catalytic converter).

3. Inspect and Replace the Catalytic Converter

• Tools Required: Jack and jack stands, socket set, exhaust pipe cutter (if necessary).
• Raise the vehicle and support it securely on jack stands.
• Remove any heat shields or brackets securing the catalytic converter.
  • Sub-step: Cut or unbolt the exhaust pipes as needed to detach the catalytic converter.
• Install the new catalytic converter, ensuring proper alignment.
  • Sub-step: Use new gaskets if required and torque bolts to the specified value (typically around 20 lb-ft).
• Reinstall any heat shields or brackets.

4. Clear Error Codes

• Reconnect the battery.
• Use the OBD-II scanner to clear the P0420 code from the system.
• Verify that the check engine light is off after clearing the codes.