I've been having this issue with the coolant sensor on the radiator, I've checked the fluids and they're good wp is new, thermostat is new also, since February. So the coolant well go off randomly almost every day but before that the coolant sensor would pop off don't know how but it did quite a few times right now its plugged in pretty good but the light keeps going off and like i said fluids are fine

 

http://shbox.com/1/4th_gen_tech2.html#low_coolant_lamp