how to fix the P0420 code on my Honda Pilot Third Generation (2016-present)

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, oxygen sensor socket, exhaust pressure gauge, multimeter.
• Ensure the vehicle is parked on a level surface, and the engine is off. Disconnect the battery for safety.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors in the exhaust system.
  2. Use the oxygen sensor socket to remove the sensors.
  3. Inspect the threads and connectors for damage.
  4. Install new oxygen sensors following the manufacturer's specifications. Torque to recommended settings (typically around 30 lb-ft).

3. Inspect and Replace Catalytic Converter

• Sub-steps:
  1. Remove any exhaust heat shields or components obstructing access to the catalytic converter.
  2. Disconnect the exhaust pipes from the catalytic converter using a socket set.
  3. Remove the catalytic converter bolts and detach it from the exhaust system.
  4. Install the new catalytic converter, ensuring proper alignment.
  5. Torque the bolts to manufacturer specifications (typically around 25 lb-ft).

4. Check for Exhaust Leaks

• Sub-steps:
  1. Reconnect all exhaust components and check for any visible leaks.
  2. Use an exhaust pressure gauge to confirm no excessive backpressure exists.

5. Reconnect Battery and Clear Codes

• Reconnect the vehicle's battery.
• Use the OBD-II scanner to clear the P0420 code and any other stored codes.