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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the battery to ensure safety while working on electrical components.

2. Inspect and Replace Faulty Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench.
• Remove the upstream and downstream oxygen sensors from the exhaust system.
• Inspect the sensors for damage or contamination.
• If faulty, install new sensors:
  1. Apply anti-seize compound to the threads of the new O2 sensors.
  2. Install the upstream sensor and torque it to the manufacturer’s specifications (typically 30-40 ft-lbs).
  3. Install the downstream sensor and torque it similarly.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if needed).
• Remove the catalytic converter:
  1. Loosen and remove the bolts or clamps securing the converter to the exhaust system.
  2. If the converter is welded in place, use the exhaust pipe cutter to remove it.
• Install the new catalytic converter:
  1. Position the new converter in place, ensuring proper alignment.
  2. Secure it with bolts or clamps, torquing to manufacturer specifications.

4. Clear Codes and Test

• Reconnect the battery.
• Use the OBD-II scanner to clear the P0420 code.
• Start the engine and let it idle for a few minutes.
• Conduct a test drive to ensure the check engine light does not reappear.