how to diagnose P0420 code on Honda Pilot Third Generation (2016-present)

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, infrared thermometer, basic socket set, safety glasses, gloves.
• Safety Warnings: Allow the engine to cool before working on the exhaust system.

2. Replace Faulty Oxygen Sensors

1. Locate the Oxygen Sensors: Identify the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
2. Disconnect the Battery: Disconnect the negative terminal of the battery to prevent any electrical shorts.
3. Remove the Oxygen Sensors: Use an oxygen sensor socket to remove the faulty sensors. Ensure the threads are clean for the new sensors.
4. Install New Oxygen Sensors: Apply anti-seize compound to the threads of the new sensors and install them, tightening to manufacturer's specifications (usually around 30 lb-ft).
5. Reconnect the Battery: Reconnect the negative battery terminal.

3. Replace the Catalytic Converter (if necessary)

1. Remove Exhaust Components: Loosen and remove any bolts or clamps securing the catalytic converter to the exhaust system using a socket set.
2. Disconnect O2 Sensors: If applicable, disconnect the downstream oxygen sensor from the catalytic converter.
3. Remove the Catalytic Converter: Carefully remove the catalytic converter from the exhaust system, ensuring not to damage any surrounding components.
4. Install New Catalytic Converter: Position the new catalytic converter in place and secure it with bolts or clamps, ensuring proper alignment.
5. Reconnect O2 Sensors: Reconnect any oxygen sensors removed during the process.