I drained half the coolant to fix my water pump gasket. I filled the the coolant with water to make sure nothing leaked. I also replaced the thermostat 203 degrees. Once I was satisfied, I drain most the coolant out and was going to top off with concentrated coolant. I want protection for -30 degrees. This way I saved money on coolant. Well my DD ECM didn’t like that so it threw a check engine light code P0118. The P0118 code refers to issues with the Engine Coolant Temperature (ECT) circuit and its accompanying sensor. Had to go to the auto store to get the error erased. Yep, can’t use old technology on new cars. Got to have the right thermostat and correct coolant level or your ECM will puke.