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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical short circuits.
• Allow the vehicle to cool down before working on the exhaust system.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, wrench set.
• Remove the upstream (pre-catalytic converter) oxygen sensor:
  1. Use an O2 sensor socket to unscrew the sensor from the exhaust manifold.
  2. Disconnect the sensor’s electrical connector.
• Install the new oxygen sensor:
  1. Apply anti-seize compound to the threads of the new sensor.
  2. Screw the sensor into place and connect the electrical connector.
• Repeat the process for the downstream (post-catalytic converter) oxygen sensor if needed.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if needed), new gaskets.
• Remove the catalytic converter:
  1. Disconnect the exhaust pipe before the catalytic converter using a socket set.
  2. Unbolt the catalytic converter from the exhaust system.
  3. Inspect the gaskets and replace them if worn.
• Install the new catalytic converter:
  1. Position the new catalytic converter into place and secure it with new gaskets.
  2. Tighten all bolts to manufacturer specifications using a torque wrench.

4. Clear Codes and Test

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code.
• Start the vehicle and let it reach operating temperature to ensure proper function.