how to fix P0420 code on Honda Accord 10th Generation (2018-2022)

Solution

1. Preparation

• Gather tools and parts necessary for the repair.
• Ensure the vehicle is on a level surface and the engine is cool.
• Disconnect the battery to avoid electrical shocks.

2. Inspect and Repair Exhaust Leaks

• Sub-steps:
  • Visually inspect the exhaust manifold, pipes, and joints for leaks.
  • Use a smoke machine to identify leaks if necessary.
  • Tighten any loose bolts or clamps, and replace any damaged gaskets or components.

3. Oxygen Sensor Replacement (if faulty)

• Sub-steps:
  • Locate the upstream and downstream oxygen sensors.
  • Unplug the electrical connector from the oxygen sensor.
  • Use an O2 sensor socket to remove the faulty sensor.
  • Apply anti-seize compound to the threads of the new oxygen sensor.
  • Install the new sensor and reconnect the electrical connector.

4. Catalytic Converter Replacement (if necessary)

• Sub-steps:
  • Remove the exhaust pipe connected to the catalytic converter by loosening the clamps and bolts.
  • Disconnect any heat shields or brackets securing the catalytic converter.
  • Carefully remove the old catalytic converter.
  • Install the new catalytic converter, ensuring proper alignment and secure it with bolts and clamps.
  • Reconnect any heat shields or brackets removed earlier.

5. Reconnect Battery and Clear Codes

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

Tools Required:

• OBD-II scanner
• Socket set
• Oxygen sensor socket
• Torque wrench
• Smoke machine (optional)
• Multimeter

Parts Required:

• New upstream and/or downstream oxygen sensors (if necessary)
• Catalytic converter (if necessary)
• Exhaust gaskets or clamps (as needed)

Estimated Repair Time: 2-4 hours

Safety Warnings:

• Disconnect the battery before working on electrical systems.
• Allow the engine to cool before working on the exhaust system to avoid burns.