how to fix P0420 code in Honda Accord Eleventh Generation (2023-present)

Solution

1. Preparation

• Gather tools and parts.
• Disconnect the negative battery terminal to avoid electrical shorts.
• Raise the vehicle using jack stands for safety.

2. Inspect and Replace Oxygen Sensors (if necessary)

• Tools Required: O2 sensor socket, wrench set, multimeter.
• Sub-steps:
  1. Remove the upstream oxygen sensor by disconnecting the electrical connector and using the O2 sensor socket to unscrew it from the exhaust manifold.
  2. Install the new upstream oxygen sensor, tightening it to the manufacturer’s specifications (usually around 30 lb-ft).
  3. Repeat the process for the downstream oxygen sensor if it was found to be faulty during diagnostics.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if necessary).
• Sub-steps:
  1. Remove any heat shields or brackets obstructing access to the catalytic converter.
  2. Unbolt the catalytic converter from the exhaust system using the socket set, ensuring to keep any gaskets for reuse if they are in good condition.
  3. Inspect the old catalytic converter for signs of clogging or damage; if defective, replace it with a new unit.
  4. Reinstall the catalytic converter and torque the bolts to the manufacturer’s specifications (typically around 25 lb-ft).
  5. Reattach any heat shields or brackets removed earlier.

4. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code from the system.