I installed a B&M tranny cooler last week and now my low water light keeps coming on when the car is cold, but once the car heats up fully the light will go away if i shut the car down and restart it. I cheched the fluid level and it is fine, any idea what the problem is?

 

You have a bad coolant level sensor. It is located just below the radiator cap. You can take it out and clean it to see if it helps, or replace it it's not that expensive, or just unplug it, the light won't come back on then.