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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.
• Allow the engine to cool down before starting work.

2. Inspect and Replace Oxygen Sensors

1. Locate the Oxygen Sensors: Identify the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
2. Remove the sensors: Use an oxygen sensor socket to carefully unscrew both sensors.
3. Inspect the sensors: Check for any signs of damage or contamination.
4. Install new sensors: Apply anti-seize compound to the threads of the new sensors and install them. Torque to manufacturer specifications (typically around 30 lb-ft).

3. Inspect and Replace Catalytic Converter

1. Remove Exhaust Components: Depending on the design, you may need to remove the exhaust pipe or other components to access the catalytic converter.
2. Unbolt the Catalytic Converter: Use a socket set to unbolt and remove the catalytic converter from the exhaust system.
3. Inspect for Blockages: Check for any signs of internal damage or blockage.
4. Install New Catalytic Converter: Place the new converter in position and secure it with bolts. Torque bolts to manufacturer specifications (typically around 30 lb-ft).
5. Reconnect Exhaust Components: Reinstall any exhaust parts that were removed.

4. Clear Error Codes

1. Reconnect the Battery: Ensure all connections are secure.
2. Use OBD-II Scanner: Connect the scanner to the vehicle and clear the P0420 code from the system.

5. Test Drive the Vehicle

1. Monitor Performance: Drive the vehicle under various conditions to ensure the check engine light does not return.
2. Perform Emissions Test: If required, ensure the vehicle passes an emissions test.