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

Solution

1. Preparation

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

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, multimeter.
• Sub-steps:
  1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
  2. Unplug the electrical connectors from both sensors.
  3. Use the O2 sensor socket to remove the oxygen sensors from their respective locations.
  4. Inspect the threads and connectors for corrosion or damage.
  5. Install new oxygen sensors (ensure they are compatible with the 2013-2017 Honda Accord).
  6. Torque the new sensors to the manufacturer's specification (typically around 30 lb-ft).

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if needed).
• Sub-steps:
  1. Locate the catalytic converter along the exhaust system.
  2. Inspect for any signs of external damage or excessive heat (discoloration).
  3. If replacement is necessary, unbolt the catalytic converter from the exhaust manifold and the exhaust pipe.
  4. Remove the catalytic converter from the vehicle.
  5. Install the new catalytic converter and ensure all gaskets are replaced.
  6. Torque the bolts to the manufacturer's specification (typically around 25 lb-ft).

4. Reconnect Battery and Test

• Reconnect the negative battery terminal.
• Start the engine and allow it to reach operating temperature.
• Clear the codes using the OBD-II scanner.