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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the battery to ensure safety during repairs.
• Raise the vehicle using a jack and secure it on jack stands.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, multimeter
• Remove the upstream (pre-catalytic) oxygen sensor by disconnecting the electrical connector and using the O2 sensor socket.
• Inspect the sensor for damage; replace if faulty.
• Repeat the process for the downstream (post-catalytic) oxygen sensor.
• Reconnect the electrical connectors for both sensors.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, exhaust pipe cutter or saw, gasket scraper, torque wrench
• Remove the exhaust bolts securing the catalytic converter to the exhaust manifold and the exhaust pipe.
• Carefully cut or disconnect any clamps holding it in place.
• Inspect the old catalytic converter for signs of damage or clogging.
• Install a new catalytic converter, ensuring to replace any gaskets and tighten bolts to manufacturer's torque specifications.

4. Reset the Engine Control Module (ECM)

• Reconnect the battery.
• Use the OBD-II scanner to clear the P0420 code from the ECM.
• Start the vehicle and allow it to reach operating temperature.