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

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to prevent any electrical issues while working.

2. Inspect and Replace O2 Sensors

• Tools Required: O2 sensor socket, torque wrench
• Remove the upstream O2 sensor:
  • Disconnect the electrical connector.
  • Use the O2 sensor socket to unscrew the sensor from the exhaust manifold.
• Install the new upstream O2 sensor:
  • Apply anti-seize compound to the threads of the new sensor.
  • Torque to manufacturer specifications (typically around 30-40 lb-ft).
• Repeat the process for the downstream O2 sensor if necessary.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, torque wrench, cutting tool (if necessary for flanged connections)
• Inspect the catalytic converter for internal damage:
  • If rattling is heard or if it appears discolored, replacement may be necessary.
• Remove the old catalytic converter:
  • Unbolt the flanges and disconnect any brackets.
  • Cut the exhaust pipe if flanges do not allow for removal.
• Install the new catalytic converter:
  • Ensure proper alignment of the exhaust system.
  • Torque all bolts to manufacturer specifications (typically around 30-35 lb-ft).
• Reconnect all hangers and brackets.

4. Final Checks

• Reconnect the battery.
• Clear the P0420 code using the OBD-II scanner.
• Start the engine and let it idle to ensure there are no exhaust leaks.