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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the battery to prevent electrical shorts.
• Allow the engine to cool before starting work.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, multimeter
• Check the wiring and connectors of both upstream and downstream O2 sensors for damage.
• If faulty, remove the defective O2 sensor using the O2 sensor socket and install the new one. Torque the sensor to the manufacturer’s specification (typically around 30 lb-ft).
• Reconnect the electrical connectors.

3. Inspect and Replace the Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if needed)
• Remove the exhaust pipe bolts connecting to the catalytic converter. Use penetrating oil if bolts are rusty.
• If the catalytic converter is damaged, replace it with a new one. Ensure the new converter is OEM or equivalent quality.
• Reattach the exhaust pipe and torque bolts to the manufacturer's specifications (usually around 25 lb-ft).

4. Clear Codes and Test

• Reconnect the battery and use the OBD-II scanner to clear the P0420 code.
• Start the engine and let it reach operating temperature.
• Perform a test drive to ensure the check engine light does not reappear and monitor for proper operation.