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

Solution

1. Preparation

• Gather necessary tools and parts.
• Park the vehicle on a flat surface and engage the parking brake.
• Disconnect the negative battery terminal.
• Allow the engine to cool down completely.

2. Inspect Exhaust System

• Tools Required: Socket set, jack stands
• Raise the vehicle with a jack and secure it with jack stands.
• Inspect the exhaust system from the exhaust manifold to the tailpipe for any visible damage or leaks. Pay special attention to joints and connection points.
• Tighten any loose bolts or replace damaged gaskets as necessary.

3. Replace Oxygen Sensors (if faulty)

• Tools Required: O2 sensor socket, wrench
• Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
• Disconnect the electrical connectors and use the O2 sensor socket to remove each sensor.
• Install new oxygen sensors, ensuring they are torqued to the manufacturer's specifications (typically around 30-40 lb-ft).
• Reconnect the electrical connectors.

4. Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, exhaust pipe cutter (if needed), gasket scraper
• Remove the bolts securing the catalytic converter to the exhaust system using the socket set.
• If the converter is welded in place, use an exhaust pipe cutter to remove it.
• Clean the mating surfaces of the exhaust system to remove old gasket material.
• Install the new catalytic converter, ensuring proper alignment and secure fastening.
• Torque the bolts to the manufacturer's specifications (typically around 30 lb-ft).

5. Reconnect Battery and Test

• Reconnect the negative battery terminal.
• Start the engine and allow it to reach operating temperature.
• Take the vehicle for a test drive to ensure proper operation and to reset the check engine light.