2015 6.7, had the oil changed at 109k miles and the check coolant additive had been coming on. Took to dealer for oil change, figured they would have checked the additive and resent the light. 3k miles later the light has turned back on.

Does the truck actually have a way of monitoring the coolant additive or is it just coming at preset mileage?

ETA the radiator was replaced around 70k miles. I assume the coolant was flushed at the same time.

 

It comes on at preset mileages. Many of us just reset, but you can check if you feel the need.

 

 

Reset procedure here:

https://www.ford-trucks.com/forums/1...l#post16437415