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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety.
• Allow the engine to cool before working on the exhaust components.

2. Inspect and Replace Oxygen Sensors

1. Remove the Upstream Oxygen Sensor:
   • Use an O2 sensor socket to unscrew the sensor from its location.
   • Disconnect the electrical connector.
2. Install the New Oxygen Sensor:
   • Apply anti-seize compound to the threads of the new sensor.
   • Install the new sensor and connect the electrical connector.
   • Torque to manufacturer specifications (typically around 30 ft-lbs).

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

1. Remove the Catalytic Converter:
   • Unbolt the catalytic converter from the exhaust manifold and the exhaust pipe using a socket set.
   • Carefully lower the converter from its position.
2. Install the New Catalytic Converter:
   • Position the new catalytic converter and secure it with bolts.
   • Torque the bolts to manufacturer specifications (usually around 25 ft-lbs).
3. Reconnect the Exhaust System: Ensure that all connections are secure and there are no leaks.

4. Clear the Error Code

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code and reset the check engine light.