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

Solution

1. Preparation

• Gather necessary tools and parts, ensuring the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the battery to prevent any electrical issues during repairs.

2. O2 Sensor Replacement

• Tools Required: O2 sensor socket, ratchet, torque wrench
• Remove the O2 sensor located before and after the catalytic converter:
  1. Locate the pre-catalytic O2 sensor and unplug the electrical connector.
  2. Use the O2 sensor socket to unscrew the sensor from the exhaust manifold.
  3. Install the new O2 sensor in the reverse order, ensuring to torque it to manufacturer's specifications (typically around 30-40 ft-lbs).
  4. Repeat for the post-catalytic O2 sensor.

3. Catalytic Converter Inspection/Replacement

• Tools Required: Socket set, exhaust pipe cutter (if necessary), torque wrench
• If the catalytic converter is determined to be faulty:
  1. Disconnect any sensors or brackets attached to the catalytic converter.
  2. Use the exhaust pipe cutter to remove the old catalytic converter if it is welded into place.
  3. Install the new catalytic converter, ensuring proper alignment with the exhaust system.
  4. Secure all connections and torque them to the specified values.
  5. Reattach any sensors or brackets removed earlier.

4. Clear Codes and Test

• Tools Required: OBD-II scanner
• After repairs are complete:
  1. Reconnect the battery.
  2. Use the OBD-II scanner to clear the P0420 code from the vehicle's computer.
  3. Start the engine and let it warm up to operating temperature.