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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the battery to prevent electrical shorts while working on the vehicle.
• Allow the engine to cool completely before beginning repairs.

2. Inspect and Replace Oxygen Sensors (if necessary)

• Tools Required: O2 sensor socket, torque wrench, penetrating oil
• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors (usually found on the exhaust manifold and after the catalytic converter).
  2. Apply penetrating oil to the sensor threads and allow it to sit for a few minutes.
  3. Disconnect the electrical connectors from the sensors.
  4. Using the O2 sensor socket, carefully remove the sensors.
  5. Install new sensors by threading them into place and tightening to the manufacturer's specifications (usually around 30 lb-ft).
  6. Reconnect the electrical connectors.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, jack stands, exhaust clamps, penetrating oil
• Sub-steps:
  1. Raise the vehicle and secure it with jack stands.
  2. Inspect the catalytic converter for damage, clogging, or signs of overheating.
  3. If replacement is needed, disconnect the exhaust pipes from the catalytic converter using a socket set.
  4. Remove any mounting bolts or clamps securing the converter in place.
  5. Install the new catalytic converter, ensuring proper alignment with the exhaust system.
  6. Reattach all bolts and clamps, tightening to the manufacturer's specifications.

4. Clear Codes and Test Drive

• Tools Required: OBD-II scanner
• Sub-steps:
  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 allow it to reach operating temperature.
  4. Take the vehicle for a test drive to ensure the check engine light does not reappear.