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

Solution

1. Preparation

• Gather necessary tools and parts:
  • OBD-II scanner
  • Socket set
  • Torque wrench
  • Exhaust gas thermometer (for temperature differential testing)
  • Replacement catalytic converter (if necessary)
• Ensure the vehicle is parked on a level surface and the engine is cool.

2. Inspect and Test O2 Sensors

• Sub-steps:
  1. Disconnect the battery to avoid electrical shorts.
  2. Remove the upstream O2 sensor using a socket wrench.
  3. Inspect the sensor for corrosion or damage; replace if necessary.
  4. Reconnect the O2 sensor and repeat the process for the downstream sensor.
  5. Use a multimeter to check that both sensors are providing correct voltage readings.

3. Check Catalytic Converter

• Sub-steps:
  1. Use an exhaust gas thermometer to measure the inlet and outlet temperatures of the catalytic converter.
  2. If the temperature difference is less than 100°F (37.8°C), the catalytic converter may be faulty.
  3. If necessary, remove the catalytic converter by unbolting it from the exhaust system using a socket set.
  4. Inspect for internal damage or clogging and replace with a new catalytic converter if needed.

4. Reassemble and Clear Codes

• Sub-steps:
  1. Reinstall any removed components in reverse order, ensuring all bolts are torqued to the manufacturer’s specifications.
  2. Reconnect the battery.
  3. Use the OBD-II scanner to clear the P0420 code from the system.