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

Solution

1. Preparation

• Gather tools and parts.
• Ensure the vehicle is parked on a flat surface and the engine is off.
• Disconnect the battery to prevent any electrical issues.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set.
• Steps:
  1. Identify the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Remove the upstream oxygen sensor using the O2 sensor socket.
  3. Inspect the sensor for damage or contamination; replace if necessary.
  4. Repeat the removal process for the downstream oxygen sensor.
  5. Install new oxygen sensors, ensuring they are tightened to the manufacturer's specifications (typically around 30 ft-lbs).

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust hangers tool.
• Steps:
  1. If the catalytic converter is found to be faulty, unbolt the exhaust pipe connected to the catalytic converter.
  2. Remove any heat shields or brackets securing the catalytic converter.
  3. Carefully remove the catalytic converter from the exhaust system.
  4. Install the new catalytic converter in the reverse order, ensuring all bolts are torqued to the manufacturer's specifications (usually around 25-30 ft-lbs).
  5. Reinstall heat shields and brackets as needed.

4. Reset Engine Control Module (ECM)

• Tools Required: OBD-II scanner.
• Steps:
  1. Reconnect the battery.
  2. Use the OBD-II scanner to clear the P0420 code from the ECM.
  3. Perform a test drive to ensure the error code does not return.