My blue coolant light was coming on when I started my car and it would go off after the car was warm, however, after about 6 miles it would come on again and stay on. I took it to my mechanic because I thought I should replace my black temperature sensor with the green sensor. He topped off my coolant and then checked the temperature sensor. It needed adjusting-so he did that. Now the blue coolant light never comes on even when I first start the car-what gives???