how to fix P0420 code in Honda Accord 9th Generation (2013-2017)

Solution

1. Preparation

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

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench
• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Remove the electrical connectors from both oxygen sensors.
  3. Using the O2 sensor socket, unscrew and remove the sensors from the exhaust manifold and catalytic converter.
  4. Install the new oxygen sensors and hand-tighten them first. Then, torque them to the manufacturer's specification (typically around 30 ft-lbs).
  5. Reconnect the electrical connectors.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Wrench set, socket set, torque wrench
• Sub-steps:
  1. Inspect the catalytic converter for any signs of damage or clogging.
  2. If replacement is needed, unbolt the catalytic converter from the exhaust pipes using the appropriate socket.
  3. Install the new catalytic converter, ensuring proper alignment with exhaust pipes.
  4. Torque the bolts to the manufacturer's specifications (refer to service manual for exact torque values).
  5. Reconnect any hangers or brackets that were removed.

4. Reset the Engine Control Unit (ECU)

• Sub-steps:
  1. Reconnect the battery.
  2. Use the OBD-II scanner to clear the P0420 code from the ECU.
  3. Start the engine and allow it to reach normal operating temperature.