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

Solution

1. Preparation

• Gather tools and parts necessary for repair.
• Disconnect the vehicle's battery to ensure safety.
• Raise the vehicle securely on jack stands.

2. Inspect and Replace Oxygen Sensors (if necessary)

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
• Remove the connectors and use the O2 sensor socket to unscrew the sensors.
• Install new sensors in reverse order, tightening to the manufacturer's specified torque (usually around 30 lb-ft).

3. Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, cutting tool for exhaust pipe (if needed), gasket scraper, torque wrench.
• Remove the exhaust pipe bolts securing the catalytic converter to the exhaust manifold and the tailpipe, using the socket set.
• If the catalytic converter is welded, use a cutting tool to carefully remove it, ensuring not to damage surrounding components.
• Clean the mating surfaces to ensure a proper seal with a gasket scraper.
• Install the new catalytic converter, securing it with bolts and gaskets, tightening to the manufacturer’s specified torque.

4. Reconnect Battery and Clear Codes

• Reconnect the battery terminals.
• Use the OBD-II scanner to clear the P0420 code from the vehicle’s computer.