how to fix P0420 code on Honda Accord 10th Generation (2018-2022)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the battery to prevent electrical shocks.

2. Replace Faulty Oxygen Sensor

1. Identify the faulty oxygen sensor based on diagnostic results.
2. Use a socket wrench to remove the oxygen sensor from its mounting.
3. Apply anti-seize compound to the threads of the new oxygen sensor.
4. Install the new oxygen sensor and tighten it to the manufacturer's specifications (typically 30-40 ft-lbs).
5. Reconnect the electrical connector for the oxygen sensor.

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

1. Remove any brackets or heat shields securing the catalytic converter.
2. Use a socket set to unbolt the catalytic converter from the exhaust system.
3. Inspect the gasket surfaces for damage and replace the gasket if needed.
4. Install the new catalytic converter, ensuring proper alignment.
5. Torque the bolts to the manufacturer's specifications (typically 25-30 ft-lbs).
6. Reinstall any brackets or heat shields that were removed.

4. Clear Error Codes

1. Reconnect the battery.
2. Use an OBD-II scanner to clear the P0420 code.
3. Start the engine and allow it to reach operating temperature.

Tools Required:

• OBD-II scanner
• Socket set
• Torque wrench
• Multimeter
• Oxygen sensor socket
• Anti-seize compound

Parts Required:

• New oxygen sensor (if faulty)
• New catalytic converter (if necessary)
• Exhaust gasket (if damaged)

Estimated Repair Time: 2-4 hours

Safety Warnings:

• Disconnect the battery before working on electrical systems.
• Allow the engine to cool before working on exhaust components to prevent burns.