my Honda Civic 9th Generation (2012-2015) has a code P0420 what does this mean

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

• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors.
  2. Disconnect the electrical connectors from both oxygen sensors.
  3. Use an oxygen sensor socket to remove the sensors from the exhaust manifold and catalytic converter.
  4. Install the new oxygen sensors, tightening to manufacturer's specifications (typically 30-40 lb-ft).
  5. Reconnect the electrical connectors.

3. Inspect the Catalytic Converter

• Sub-steps:
  1. Visually inspect the catalytic converter for physical damage or excessive carbon buildup.
  2. If damaged, remove the catalytic converter using a socket set to unbolt it from the exhaust system.
  3. Install a new catalytic converter, ensuring all gaskets and seals are replaced for a tight fit.
  4. Torque the bolts to the specified value (generally around 30-35 lb-ft).

4. Clear Error Codes

• Sub-steps:
  1. Reconnect the battery.
  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.