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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative battery terminal to ensure safety.
• Allow the engine to cool down to prevent burns.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench, penetrating oil.
  1. Locate the upstream and downstream oxygen sensors.
  2. Use penetrating oil on the sensor threads to ease removal.
  3. Disconnect the electrical connector for each sensor.
  4. Remove the sensors using the O2 sensor socket.
  5. Install the new upstream and downstream oxygen sensors, tightening to the manufacturer’s specified torque (usually around 30 ft-lbs).
  6. Reconnect the electrical connectors.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Jack and jack stands, socket set, torque wrench, exhaust gasket.
  1. Raise the vehicle securely on jack stands.
  2. Locate the catalytic converter in the exhaust system.
  3. Remove any bolts or clamps securing the catalytic converter to the exhaust pipes.
  4. Inspect the catalytic converter for signs of damage or blockage.
  5. If the catalytic converter is faulty, replace it with a new one, ensuring that the exhaust gasket is replaced.
  6. Reattach the catalytic converter to the exhaust pipes, tightening bolts to the manufacturer’s specified torque.

4. Clear Code and Test Drive

• Use an OBD-II scanner to clear the P0420 code.
• Reconnect the negative battery terminal.
• Start the engine and allow it to reach operating temperature.
• Take the vehicle for a test drive to ensure the check engine light does not reappear.