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 battery to prevent electrical shocks.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench, multimeter
  • 1. Locate the upstream (pre-cat) and downstream (post-cat) oxygen sensors.
  • 1. Disconnect the wiring harness from both sensors.
  • 1. Use the O2 sensor socket to remove the sensors from the exhaust manifold and catalytic converter.
  • 1. Install new oxygen sensors, torquing them to manufacturer specifications (usually around 30-40 lb-ft).
  • 1. Reconnect the wiring harnesses.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust gasket, replacement catalytic converter
  • 1. Raise the vehicle safely and support it with jack stands.
  • 1. Locate the catalytic converter along the exhaust system.
  • 1. Remove any heat shields or brackets that may obstruct access.
  • 1. Unbolt the catalytic converter from the exhaust manifold and the exhaust pipe.
  • 1. Carefully remove the old catalytic converter and replace it with the new one, ensuring proper alignment.
  • 1. Torque the bolts to the manufacturer’s specifications (typically around 25-35 lb-ft).
  • 1. Reinstall any heat shields or brackets that were removed.

4. Clear Codes and Test

• Tools Required: OBD-II scanner
  • 1. Reconnect the battery.
  • 1. Use the OBD-II scanner to clear the P0420 code.
  • 1. Start the engine and allow it to reach operating temperature.
  • 1. Test drive the vehicle to ensure the check engine light does not reappear.