how to fix P0420 code on Honda Pilot YF3 (2016-2022)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Ensure the vehicle is parked on a level 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 by:
  1. Locating the sensor (usually near the exhaust manifold).
  2. Using the O2 sensor socket, unscrew the sensor counter-clockwise.
  3. Install the new sensor and torque to manufacturer specifications (generally around 30 lb-ft).
• Repeat for the downstream sensor if necessary.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust clamp tool
• Lift the vehicle using a jack and secure with jack stands.
• Remove the exhaust heat shield (if applicable) to access the catalytic converter.
• Unbolt the catalytic converter from the exhaust system:
  1. Remove bolts at both the inlet and outlet flanges.
  2. Carefully detach the converter from the exhaust pipes.
• Install the new catalytic converter:
  1. Align the converter with the exhaust pipes.
  2. Hand-tighten bolts, then torque to specifications (usually around 25-30 lb-ft).
• Reinstall the heat shield.

4. Reconnect Battery and Clear Codes

• Reconnect the battery terminals and ensure they are tight.
• Use the OBD-II scanner to clear the P0420 code.
• Start the engine and let it idle for a few minutes to monitor for any new codes.