how to fix Honda Civic 10th Generation (2016-2021) P0420 code for catalytic converter

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 shorts.

Tools Required:

• OBD-II scanner
• Multimeter
• Socket set
• Torque wrench
• Jack and jack stands

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors.
  2. Disconnect the electrical connectors from both sensors.
  3. Using a socket wrench, remove the sensors from the exhaust system.
  4. Install new oxygen sensors, ensuring proper torque (typically 30-40 ft-lbs).
  5. Reconnect the electrical connectors.

3. Inspect and Replace Catalytic Converter (if necessary)

• Sub-steps:
  1. Remove the exhaust pipe connected to the catalytic converter using a socket set.
  2. Unbolt the catalytic converter from its mounting points.
  3. Inspect the catalytic converter for any signs of damage or clogging.
  4. If needed, install a new catalytic converter, ensuring proper alignment and secure with bolts to the specified torque (typically 30-40 ft-lbs).
  5. Reconnect the exhaust pipe and secure all clamps.

4. Reset the OBD-II System

• Sub-steps:
  1. Reconnect the battery.
  2. Use the OBD-II scanner to clear the fault codes from the system.
  3. Start the engine and allow it to reach operating temperature.