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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the vehicle's battery to ensure safety during repairs.
• Lift the vehicle using a jack and secure it with jack stands.

2. Inspect and Replace Oxygen Sensors

1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
2. Using a socket wrench, carefully unscrew both oxygen sensors from their respective locations.
3. Inspect the sensors for damage or excessive wear.
4. If replacement is needed, install new oxygen sensors, ensuring to apply anti-seize compound on the threads.
5. Torque the sensors to the manufacturer’s specifications (typically around 30 ft-lbs).

3. Inspect and Replace Catalytic Converter

1. If the oxygen sensors are functioning correctly, proceed to inspect the catalytic converter.
2. Remove any heat shields or brackets securing the catalytic converter.
3. Using a cutting tool or exhaust pipe cutter, carefully cut the exhaust pipes connected to the catalytic converter.
4. Remove the old catalytic converter and clean the mating surfaces on the exhaust pipes.
5. Install the new catalytic converter, ensuring proper alignment with the exhaust pipes.
6. Secure it with new gaskets and bolts, torquing them to manufacturer specifications (typically around 25 ft-lbs).

4. Reconnect Battery and Clear Codes

1. Reconnect the vehicle's battery terminals securely.
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.