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

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the negative terminal of the battery.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set
• Sub-steps:
  1. Locate the upstream (pre-catalytic) oxygen sensor; it is usually positioned before the catalytic converter.
  2. Remove the electrical connector from the oxygen sensor.
  3. Using the O2 sensor socket, unscrew the old sensor from the exhaust pipe.
  4. Install the new oxygen sensor by threading it into the exhaust pipe and tightening it to the manufacturer's torque specifications (usually around 30 ft-lbs).
  5. Reconnect the electrical connector.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust hanger removal tool
• Sub-steps:
  1. Locate the catalytic converter, typically found along the exhaust system after the engine.
  2. Use an exhaust hanger removal tool to detach any hangers holding the catalytic converter in place.
  3. Remove the bolts securing the catalytic converter to the exhaust pipe and exhaust manifold using the socket set.
  4. Inspect the catalytic converter for internal damage or blockage.
  5. If damaged, install the new catalytic converter in the reverse order of removal, ensuring proper torque on all bolts (typically 30 ft-lbs).
  6. Reattach any hangers and ensure the exhaust system is secure.

4. Clear Codes and Test Drive

• Sub-steps:
  1. Reconnect the negative battery terminal.
  2. Use the OBD-II scanner to clear the P0420 code.
  3. Start the engine and allow it to reach operating temperature.
  4. Take the vehicle for a test drive to ensure the issue is resolved.