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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the negative terminal of the battery to ensure safety.
• Allow the engine to cool before working on it.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors.
  2. Unplug the electrical connectors from both sensors.
  3. Use an O2 sensor socket to remove the sensors from the exhaust system.
  4. Install the new oxygen sensors and torque them to the manufacturer’s specifications (typically 30-40 lb-ft).
  5. Reconnect the electrical connectors to both sensors.

3. Inspect and Replace Catalytic Converter (if needed)

• Sub-steps:
  1. Locate the catalytic converter in the exhaust system.
  2. Disconnect any exhaust hangers or clamps holding the catalytic converter in place.
  3. Remove the catalytic converter by loosening the bolts at the flanges.
  4. Inspect the old catalytic converter for signs of damage or clogging.
  5. Install the new catalytic converter, ensuring proper alignment with exhaust flanges.
  6. Torque the bolts to the manufacturer's specifications (typically 20-25 lb-ft).
  7. Reattach any hangers or clamps removed during disassembly.

4. Clear Codes and Test

• Sub-steps:
  1. Reconnect the negative battery terminal.
  2. Use the OBD-II scanner to clear the P0420 code from the vehicle’s computer.
  3. Start the engine and allow it to reach operating temperature.
  4. Take the vehicle for a test drive, monitoring the performance and checking for any reoccurrence of the P0420 code.