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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety while working on the vehicle.
• Allow the engine to cool completely before starting work.

2. Inspect and Replace Oxygen Sensors (if necessary)

• Tools Required: O2 sensor socket, torque wrench
• Remove the upstream and downstream oxygen sensors using the O2 sensor socket.
• Inspect the sensors for carbon buildup or damage; if necessary, replace with new OEM sensors.
• Install new sensors and torque to the manufacturer's specifications (usually around 30 Nm or 22 lb-ft).

3. Inspect and Replace the Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if needed), gasket scraper
• Remove the exhaust pipe connections to the catalytic converter using the socket set.
• If the catalytic converter is damaged or restricted, cut it out using an exhaust pipe cutter.
• Install the new catalytic converter, ensuring proper alignment with exhaust flanges.
• Use new gaskets and torque all bolts to specifications (typically around 40 Nm or 30 lb-ft).

4. Reconnect Battery and Clear Codes

• Reconnect the negative terminal of the battery.
• Use an OBD-II scanner to clear the P0420 code from the vehicle's computer.

5. Test System and Monitor

• Start the engine and allow it to reach operating temperature.
• Monitor the O2 sensor readings and test drive the vehicle to ensure the check engine light remains off and performance is restored.