how can I fix the P0420 code on my Honda Accord 10th Generation (2018-2022)?

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to avoid any electrical shorts.
• Ensure the vehicle is parked on a level surface and the engine is cool.

2. Inspect and Replace Oxygen Sensors

1. Locate Oxygen Sensors: Identify the upstream and downstream oxygen sensors on the exhaust system.
2. Remove Old Sensors: Use an oxygen sensor socket to carefully unscrew and remove the old sensors from their housings.
3. Install New Sensors: Apply a small amount of anti-seize compound to the threads of the new sensors. Screw them into place and tighten to the manufacturer's specifications (usually around 30-40 ft-lbs).
4. Reconnect Wiring: Reconnect the electrical connectors to the sensors.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Remove Exhaust Components: If the catalytic converter needs replacement, first remove the exhaust components connected to it. This may include unbolting flanges and removing hangers.
2. Remove Catalytic Converter: Unscrew and remove the old catalytic converter from the exhaust system.
3. Install New Catalytic Converter: Position the new catalytic converter in place and secure it with bolts. Ensure all gaskets are replaced and tightened to the specified torque.
4. Reassemble Exhaust System: Reattach all components you removed, ensuring proper alignment and seal.

4. Clear Codes and Test

1. Reconnect Battery: Reconnect the battery terminals.
2. Clear OBD-II Codes: Use the scanner to clear the P0420 code from the vehicle’s computer.
3. Test Drive: Drive the vehicle for a short distance under various conditions to ensure the issue has been resolved and the check engine light does not return.