The contact owns a 2017 Ford Mustang. The contact stated while driving approximately 40 MPH, the message ‘High Temperature — Pull Over’ was displayed on the instrument panel. The contact was consistently adding coolant to the coolant reservoir for the vehicle to return to normal operation. The failure had occurred on several occasions. The contact stated that there was no warning light illuminated. The vehicle was taken back to the residence. The vehicle was not diagnosed or repaired. The manufacturer was notified of the failure and referred the contact to the NHTSA Hotline to report the failure. The failure mileage was approximately 80,000.