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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the vehicle to cool before starting work.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench, penetrating oil.
• Remove the upstream and downstream oxygen sensors:
  1. Apply penetrating oil to the sensor threads if stuck.
  2. Use the O2 sensor socket to unscrew the sensors.
• Install the new oxygen sensors:
  1. Apply anti-seize compound to the threads of the new sensors.
  2. Torque the sensors to the manufacturer's specifications (usually around 30 ft-lbs).

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, jack and jack stands, exhaust gasket, torque wrench.
• Remove the catalytic converter:
  1. Raise the vehicle and secure it on jack stands.
  2. Loosen and remove the bolts connecting the catalytic converter to the exhaust manifold and the exhaust pipe.
  3. Inspect and replace the exhaust gasket if damaged.
• Install the new catalytic converter:
  1. Position the new catalytic converter and align it with the exhaust system.
  2. Bolt it into place and torque the bolts to the manufacturer's specifications.
  3. Reinstall any heat shields if applicable.

4. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear any trouble codes from the ECM.