how to fix P0420 code on my Honda Civic 11th Generation (2022-Present)

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, socket set, torque wrench, jack and jack stands.
• Safety Warnings: Disconnect the battery before working on electrical systems. Allow the engine to cool before working on the exhaust system.

2. Repair or Replace Oxygen Sensors

1. If the oxygen sensor readings are outside the normal range, remove the faulty oxygen sensor:
   • Use a socket to loosen and remove the sensor from the exhaust manifold (pre-catalytic) or after the catalytic converter (post-catalytic).
   • Disconnect the electrical connector.
2. Install the new oxygen sensor:
   • Apply anti-seize compound to the threads of the new sensor (if required).
   • Torque the sensor to the manufacturer's specified value (typically around 30 lb-ft).
   • Reconnect the electrical connector.

3. Inspect and Replace Catalytic Converter

1. If the catalytic converter is damaged or the oxygen sensors are functioning correctly, the catalytic converter may need replacement:
   • Raise the vehicle securely with jack stands.
   • Remove any heat shields or brackets obstructing access to the catalytic converter.
   • Unbolt the catalytic converter from the exhaust manifold and the exhaust pipe, using a socket set.
   • Replace the old catalytic converter with a new one, ensuring proper alignment.
   • Torque the bolts to the manufacturer's specifications.

4. Reconnect and Clear Codes

1. Reconnect the battery and use the OBD-II scanner to clear the P0420 code.
2. Start the engine and allow it to reach operating temperature.