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

Solution

1. Preparation

• Gather tools and parts needed 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 (pre-cat) oxygen sensor:
  1. Use an O2 sensor socket to unscrew the sensor from the exhaust manifold.
  2. Disconnect the wiring harness from the sensor.
• Install the new upstream oxygen sensor:
  1. Apply anti-seize compound to the threads of the new sensor.
  2. Thread the new sensor into the exhaust manifold by hand, then torque to the manufacturer's specifications (typically around 30 Nm).
  3. Reconnect the wiring harness.
• Repeat the process for the downstream (post-cat) oxygen sensor.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust hangers tool.
• Remove the catalytic converter:
  1. Unbolt the catalytic converter from the exhaust manifold and the mid-pipe.
  2. Use an exhaust hanger tool to detach any hangers holding the converter.
• Install the new catalytic converter:
  1. Position the new converter and secure it with the bolts to the exhaust manifold and mid-pipe.
  2. Torque all fasteners to the manufacturer's specifications (typically around 40-50 Nm).
  3. Reattach any exhaust hangers.

4. Clear Codes and Test Drive

• Use an OBD-II scanner to clear the P0420 code from the system.
• Reconnect the battery.
• Test drive the vehicle for a minimum of 15 minutes to allow the system to recheck catalytic converter efficiency.