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

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, jack and jack stands, multimeter, smoke machine (optional)
• Ensure the vehicle is parked on a flat surface and engage the parking brake.
• Disconnect the negative terminal of the battery to prevent electrical shorts.

2. Inspect and Replace O2 Sensors

1. Locate the upstream and downstream O2 sensors on the exhaust system.
2. Using a socket wrench, carefully remove the O2 sensors.
3. Inspect the threads for damage; if necessary, clean or replace the sensor.
4. Install new O2 sensors by threading them into place and tightening to the manufacturer's specified torque (typically around 30 Nm).
5. Reconnect the electrical connectors for both sensors.

3. Inspect and Replace Catalytic Converter (if necessary)

1. If the catalytic converter is damaged or the P0420 persists after O2 sensor replacement, proceed to replace the catalytic converter.
2. Use a socket wrench to remove the bolts securing the catalytic converter to the exhaust manifold and the exhaust pipe.
3. Carefully detach the catalytic converter and inspect the exhaust flanges for damage.
4. Install the new catalytic converter, ensuring proper alignment and sealing with new gaskets as needed.
5. Torque the bolts to the manufacturer's specifications (typically around 25 Nm for flange bolts).

4. Reconnect Battery

• Reattach the negative terminal of the battery securely.

5. Clear Error Codes

• Use an OBD-II scanner to clear the P0420 code from the ECU.
• Start the engine and allow it to reach operating temperature.