my Ford Mustang S650 (2024-Present) has a check engine light and code P0420, how to fix?

Solution

1. Preparation

• Gather tools and parts.
• Disconnect the battery to prevent electrical shorts during repairs.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench
• Inspect the upstream oxygen sensor for any signs of damage or contamination.
• If faulty, disconnect the electrical connector and remove the sensor using the O2 sensor socket.
• Install the new oxygen sensor, ensuring it is torqued to the manufacturer's specifications (usually around 30-40 lb-ft).
• Reconnect the electrical connector.

3. Examine and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, jack stands, exhaust gasket (if needed)
• Raise the vehicle and support it securely with jack stands.
• Remove any heat shields or components obstructing access to the catalytic converter.
• Disconnect the exhaust pipes from the catalytic converter, noting the orientation for reassembly.
• Remove the catalytic converter from its mounting brackets.
• Install the new catalytic converter, ensuring proper alignment with exhaust pipes and mounts.
• Reattach any heat shields and components that were removed.

4. Clear Diagnostic Codes

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