how to fix Honda Accord 9th Generation (2013-2017) P0420 code and reduce emissions

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Ensure the vehicle is parked on a level surface and secure it with wheel chocks.
• Disconnect the battery to ensure safety while working on electrical components.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench, multimeter.
• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors in the exhaust system.
  2. Disconnect the electrical connectors from both sensors.
  3. Using the O2 sensor socket, remove the sensors from the exhaust system.
  4. Install the new sensors and torque to manufacturer specifications (typically around 30 ft-lbs).
  5. Reconnect the electrical connectors securely.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, torque wrench, cutting tool (if necessary), gasket scraper.
• Sub-steps:
  1. Locate the catalytic converter in the exhaust system.
  2. If necessary, cut the exhaust pipes using a cutting tool for easier removal.
  3. Remove the bolts securing the catalytic converter to the exhaust system using a socket set.
  4. Clean the mating surfaces of the exhaust pipes using a gasket scraper to ensure a proper seal.
  5. Install the new catalytic converter, aligning it properly, and secure it with bolts to the specified torque (usually around 40 ft-lbs).
  6. If applicable, reattach any exhaust heat shields.

4. Reconnect Battery and Clear Codes

• Reconnect the battery terminals securely.
• Use the OBD-II scanner to clear any stored trouble codes from the vehicle’s engine control module (ECM).