how to fix P0420 code on Honda Accord Eleventh Generation (2023-present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety while working on electrical components.

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. Disconnect Electrical Connectors: Carefully unplug the connectors from both sensors.
3. Remove Sensors: Use an oxygen sensor socket to unscrew and remove the sensors. Replace them if they show signs of wear or malfunction.
4. Install New Sensors: Apply anti-seize compound to the threads of the new sensors and install them. Torque to manufacturer's specifications (usually around 30-35 lb-ft).

3. Inspect and Replace the Catalytic Converter

1. Assess the Catalytic Converter: If the oxygen sensors are functioning correctly, inspect the catalytic converter for clogs or damage.
2. Remove the Catalytic Converter:
   • Loosen and remove the bolts connecting the exhaust pipes to the catalytic converter using a socket set.
   • Carefully detach the catalytic converter.
3. Install New Catalytic Converter:
   • Position the new catalytic converter and secure it with the bolts.
   • Torque the bolts to the manufacturer's specifications (typically around 25-30 lb-ft).

4. Clearing the Code

1. Reconnect the Battery: Ensure the battery is reconnected securely.
2. Clear OBD-II Codes: Use the OBD-II scanner to erase the P0420 code from the ECU.
3. Test Drive the Vehicle: Drive the vehicle for a short distance to allow the ECU to re-evaluate the system.