how to fix P0420 code in Honda Accord 9th Generation (2013-2017)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety during repairs.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, multimeter
• Remove the upstream oxygen sensor (before the catalytic converter):
  1. Disconnect the electrical connector.
  2. Use the O2 sensor socket to unscrew the sensor.
  3. Install the new upstream sensor and reconnect the electrical connector.
• Repeat the process for the downstream oxygen sensor (after the catalytic converter) if it shows signs of failure.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, torque wrench, gasket scraper, exhaust pipe cutter
• Safely lift the vehicle and support it on jack stands.
• Remove the exhaust heat shield if necessary.
• Unbolt the catalytic converter from the exhaust pipe:
  1. Use a socket set to remove the flange bolts.
  2. Gently tap the converter with a rubber mallet to break any sealant.
• Install the new catalytic converter:
  1. Place a new gasket on the flange.
  2. Bolt the converter back onto the exhaust system and torque to manufacturer specifications.

4. Reconnect Battery and Clear Codes

• Reconnect the battery terminals.
• Use the OBD-II scanner to clear the P0420 code and any other related codes.

5. Test Drive

• Drive the vehicle for at least 20-30 minutes to allow the computer to monitor the exhaust system and verify that the problem is resolved.