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

Solution

1. Preparation

• Gather tools and parts required.
• Disconnect the battery to ensure safety.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Sub-steps:
  1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
  2. Use the O2 sensor socket to carefully unscrew the faulty sensor.
  3. Install the new sensor, ensuring it is tightened to the manufacturer's specifications (typically around 30 Nm or 22 lb-ft).
  4. Reconnect the battery.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, jack and jack stands, exhaust gasket, torque wrench.
• Sub-steps:
  1. Raise the vehicle using a jack and secure it with jack stands.
  2. Disconnect the exhaust pipes from the catalytic converter using the socket set.
  3. Remove the old catalytic converter. If it is bolted, use the torque wrench to loosen the bolts.
  4. Clean the mating surfaces on the exhaust pipes.
  5. Install the new catalytic converter, ensuring the exhaust gasket is correctly placed.
  6. Tighten the bolts to the manufacturer's specifications (usually around 30 Nm or 22 lb-ft).
  7. Lower the vehicle.

4. Clear Fault Codes

• Use the OBD-II scanner to clear the P0420 code from the vehicle's computer.
• Start the engine and let it idle for a few minutes.