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

Solution

1. Preparation

• Gather tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Remove the upstream and downstream oxygen sensors:
  1. Locate the upstream O2 sensor (before the catalytic converter) and unplug the electrical connector.
  2. Use the O2 sensor socket to unscrew the sensor from the exhaust pipe.
  3. Repeat for the downstream O2 sensor (after the catalytic converter).
• Install new oxygen sensors:
  1. Apply anti-seize compound to the threads of the new O2 sensors.
  2. Thread the new sensors into their respective positions and torque them to the manufacturer's specifications (typically 30 ft-lbs).
  3. Reconnect the electrical connectors.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust gasket.
• Remove the catalytic converter:
  1. Disconnect the exhaust pipes from the catalytic converter by removing any bolts or clamps.
  2. If applicable, unbolt the mounting brackets holding the catalytic converter in place.
  3. Carefully remove the catalytic converter from the vehicle.
• Install the new catalytic converter:
  1. Position the new converter in place and secure it with the mounting brackets.
  2. Reconnect the exhaust pipes and tighten the bolts to the specified torque (typically around 25-30 ft-lbs).
  3. Replace any gaskets if necessary to ensure a proper seal.

4. Reconnect Battery and Clear Codes

• Reconnect the vehicle's battery.
• Use the OBD-II scanner to clear the P0420 code and any other stored codes.