My 1999 Xk8's coolant temperature light in the instrument panel stays on most of the time. Even when I start the car with a stone-cold engine, that little light is illuminated. After the engine is warmed up, that little light will eventually go out, and then come back on again, and out again, etc. The coolant level is not low, and the sensor is new. Anyone else experiencing this? I'm thinking something in the wiring, connector to the sensor, or even a bad sensor even though is new. One other thing. When I start the car if that light is on, the engine has a rough idle until it warms up. With or without the light being on or off, the rough idle goes away when the engine warms up. Ideas? Thank you, Warren C. Warburton USA