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

Solution

1. Preparation

• Gather tools including OBD-II scanner, multimeter, socket set, and exhaust backpressure gauge.
• Disconnect the battery to ensure safety.
• Allow the engine to cool before starting work on the exhaust system.

2. Inspect and Replace Oxygen Sensors

• 2.1 Remove the upstream oxygen sensor:
  • Use a socket wrench to carefully unscrew the sensor.
  • Disconnect the electrical connector.
• 2.2 Install the new upstream oxygen sensor:
  • Connect the electrical connector and screw in the sensor.
  • Torque to manufacturer specifications (usually around 30 ft-lbs).
• 2.3 Repeat for the downstream oxygen sensor if it shows faulty readings.

3. Inspect and Replace Catalytic Converter

• 3.1 Remove the catalytic converter:
  • Unbolt the exhaust flanges connecting it to the exhaust manifold and mid-pipe.
  • Carefully lower it from the vehicle.
• 3.2 Install the new catalytic converter:
  • Position it correctly and secure it with the bolts.
  • Torque to manufacturer specifications.

4. Clear Error Codes

• Use the OBD-II scanner to clear the P0420 code from the vehicle’s computer.
• Reconnect the battery.

5. Test the System

• Start the engine and allow it to reach operating temperature.
• Monitor the OBD-II system for any reoccurrence of the P0420 code.