Why did the Fail Safe Mode on my 2010 F350 come on?

The Fail Safe Mode on your 2010 F350 likely activated due to a detected issue with the engine or transmission, such as a malfunctioning sensor, overheating, or low fluid levels. This mode is designed to protect the vehicle from further damage by limiting performance. To identify the specific cause, it's advisable to check for any diagnostic trouble codes (DTCs) using an OBD-II scanner and consult a qualified mechanic for a thorough inspection.