how to fix Ford Mustang S650 (2024-Present) P0420 code

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, socket set, torque wrench, temperature gauge, safety glasses, gloves.
• Ensure the engine is cool and the vehicle is parked on a level surface.
• Disconnect the battery to prevent electrical shock.

2. Inspect and Replace Oxygen Sensors

1. Locate the oxygen sensors: one before the catalytic converter (upstream) and one after (downstream).
2. Remove the upstream oxygen sensor:
   • Use a socket wrench to loosen and remove the sensor.
   • Check the condition of the sensor; if it’s corroded or damaged, replace it.
3. Remove the downstream oxygen sensor using the same method.
4. Install the new oxygen sensors:
   • Apply anti-seize compound to the threads if necessary.
   • Torque the sensors to the manufacturer’s specification (typically around 30 ft-lbs).
5. Reconnect the battery.

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

1. If the catalytic converter is damaged or has failed the temperature test, it will need replacement.
2. Remove the exhaust pipe connected to the catalytic converter:
   • Use a socket wrench to loosen the bolts and remove any clamps.
3. Disconnect the catalytic converter from the exhaust manifold:
   • Remove the bolts securing it to the manifold and detach it.
4. Install the new catalytic converter:
   • Position the new unit and secure it to the exhaust manifold with bolts.
   • Reconnect the exhaust pipe and secure with clamps and bolts.
5. Ensure all connections are tight and leak-free.

4. Clear Codes and Test Drive

1. Use the OBD-II scanner to clear the P0420 code.
2. Start the engine and allow it to reach operating temperature.
3. Take the vehicle for a test drive to ensure the check engine light does not reappear and that performance is restored.