how to fix Honda Accord Eleventh Generation (2023-present) check engine light P0420 code

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to avoid electrical issues.

2. Inspect Oxygen Sensors

• Remove the upstream (pre-catalytic) oxygen sensor using an O2 sensor socket.
• Inspect the sensor for damage; clean or replace if necessary.
• Repeat for the downstream (post-catalytic) oxygen sensor.

3. Examine Catalytic Converter

• Raise the vehicle securely on jack stands.
• Inspect the catalytic converter for signs of damage, such as dents or cracks.
• Use a vacuum gauge to test for blockage; replace the catalytic converter if necessary.

4. Repair or Replace Components

• If oxygen sensors are faulty, replace them with new OEM sensors.
• If the catalytic converter is damaged, remove it and install a new one, ensuring to torque the bolts to manufacturer specifications (typically around 30-40 ft-lbs).

5. Clear Codes and Test

• Reconnect the battery.
• Use the OBD-II scanner to clear the P0420 code.
• Start the engine and let it reach operating temperature.

Tools Required:

• OBD-II scanner
• Oxygen sensor socket
• Torque wrench
• Jack and jack stands
• Vacuum gauge

Parts Required:

• Upstream oxygen sensor (if needed)
• Downstream oxygen sensor (if needed)
• Catalytic converter (if damaged)

Estimated Repair Time: 2-4 hours

Safety Warnings:

• Disconnect the battery before working on electrical systems.
• Allow the engine to cool before inspecting the exhaust system to avoid burns.