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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the battery to prevent electrical shocks.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench
• Remove the upstream oxygen sensor (typically located before the catalytic converter).
  • Use an O2 sensor socket and carefully unscrew it.
• Install the new upstream oxygen sensor.
  • Torque to manufacturer's specifications (usually around 30 ft-lbs).
• Repeat the process for the downstream oxygen sensor if necessary.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust hanger removal tool
• Remove the exhaust pipes connected to the catalytic converter.
  • Use a socket set to unbolt the flanges and remove any exhaust hangers.
• Inspect the catalytic converter for physical damage or clogging.
• If replacement is needed, install the new catalytic converter.
  • Follow the manufacturer's torque specifications for all bolts (often around 40-50 ft-lbs).
  • Ensure all gaskets are replaced to prevent leaks.

4. Reconnect Battery and Clear Codes

• Reconnect the battery terminals securely.
• Use the OBD-II scanner to clear the P0420 code.

5. Conduct a Test Drive

• Take the vehicle for a short drive to allow the engine to reach operating temperature and check for any reoccurring codes.