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

Solution

1. Preparation

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

2. Inspect and Replace Oxygen Sensors

• Tools Required: OBD-II scanner, socket set, multimeter.
• Remove the upstream and downstream oxygen sensors using the socket set.
• Inspect the wiring harness for damage or corrosion.
• Test the sensors with a multimeter to ensure proper voltage and resistance readings.
• Replace any faulty oxygen sensors with new ones.

3. Examine and Replace the Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if necessary).
• Raise the vehicle securely on jack stands.
• Remove the bolts securing the catalytic converter to the exhaust system using the socket set.
• If necessary, cut the exhaust pipe with an exhaust pipe cutter to facilitate removal.
• Install the new catalytic converter, ensuring proper alignment.
• Torque the bolts to the manufacturer's specifications (typically around 30-40 ft-lbs, but verify from the service manual).

4. Reset the OBD-II System

• Reconnect the battery.
• Use an OBD-II scanner to clear the P0420 code from the vehicle's computer.
• Start the engine and allow it to run for a few minutes to check for any new codes.