how to fix P0420 code on Honda Pilot YF4 (2023-Present)

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.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench
• Remove the upstream oxygen sensor:
  1. Use an O2 sensor socket to carefully unscrew the sensor from the exhaust manifold.
  2. Inspect the sensor for damage or corrosion.
  3. Install the new sensor and torque to manufacturer specification (typically 30 lb-ft).
• Repeat for the downstream oxygen sensor if necessary.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, jack and jack stands, exhaust pipe cutter (if necessary)
• Raise the vehicle and secure it on jack stands.
• Inspect the catalytic converter visually and by tapping with a rubber mallet (listen for rattling).
• If replacement is needed:
  1. Disconnect the exhaust pipes from the catalytic converter using a socket set.
  2. Remove any mounting bolts and brackets securing the converter.
  3. Install the new catalytic converter and securely fasten it using the original bolts and any new gaskets as required.
  4. Ensure all connections are tight to prevent exhaust leaks.

4. Clear Error Codes

• Reconnect the battery and use the OBD-II scanner to clear the P0420 code.
• Start the engine and let it idle for a few minutes.