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

Solution

1. Preparation

• Tools Needed: OBD-II scanner, multimeter, socket set, torque wrench, exhaust pipe cutter (if necessary), jack and jack stands.
• Safety Warnings: Ensure the vehicle is on a flat surface, and wear safety goggles and gloves. Disconnect the battery before working on electrical components.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
  2. Disconnect the electrical connectors from both sensors.
  3. Use a socket wrench to remove the sensors from the exhaust system.
  4. Inspect the threads and sealing surfaces for damage. Clean if necessary.
  5. Install new oxygen sensors, tightening them to the manufacturer's specifications (typically 30 lb-ft).
  6. Reconnect the electrical connectors securely.

3. Check and Replace Catalytic Converter (if necessary)

• Sub-steps:
  1. If oxygen sensors are functioning correctly, inspect the catalytic converter for physical damage or blockage.
  2. If replacement is needed, use an exhaust pipe cutter to remove the old catalytic converter from the exhaust system.
  3. Install the new catalytic converter, ensuring proper alignment and fit.
  4. Use a torque wrench to tighten all exhaust connections to manufacturer specifications.
  5. Reconnect any sensors or wiring that were disconnected during the process.

4. Reconnect Battery and Clear Codes

• Sub-steps:
  1. Reconnect the negative battery terminal.
  2. Use the OBD-II scanner to clear the P0420 code from the vehicle’s computer.
  3. Start the engine and let it idle for a few minutes.