how to fix P0420 code on Honda Civic 9th Generation (2012-2015)

Solution

1. Preparation

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

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors on the exhaust system.
  2. Disconnect the electrical connectors from both sensors.
  3. Use an oxygen sensor socket to remove the faulty sensors.
  4. Install new oxygen sensors, tightening them to the manufacturer's specified torque (typically around 30 lb-ft).
  5. Reconnect the electrical connectors to the new sensors.

3. Inspect and Replace Catalytic Converter

• Sub-steps:
  1. Safely raise the vehicle using jack stands.
  2. Locate the catalytic converter along the exhaust system.
  3. Unbolt the catalytic converter from the exhaust manifold and the exhaust piping.
  4. Remove the old catalytic converter and install the new one, ensuring proper alignment.
  5. Tighten the bolts to the specified torque (usually around 30 lb-ft).
  6. Reconnect any heat shields or additional components removed during the process.

4. Reconnect Battery and Clear Codes

• Sub-steps:
  1. Reconnect the negative terminal of the battery.
  2. Use the OBD-II scanner to clear the P0420 code from the system.
  3. Start the engine and let it idle for a few minutes.