Redator fan will not shut off when the vehicle is shut off.

Hi, this is Bo, an auto expert on RepairPal's Car Genius team! It's like the fan has its own plan! It sounds like a cooling fan relay issue. When the relay gets stuck or malfunctions, it can keep the radiator fan running even after the engine is turned off. The temperature gauge dropping to zero on the highway indicates a potential problem with the coolant temperature sensor or wiring, confusing the fan control system. Have a mechanic inspect and possibly replace the cooling fan relay and check the temperature sensor and wiring. This should resolve the issue and prevent further battery drain. Good luck! If you have any other questions, please call us at 877-913-1554! We'll gladly find you a certified RepairPal shop in your area!