2008 Grand Marqui LS 4.6L code P0128 ECTSensor

If you are facing the engine its to the right of the alternator. But.... I think you have an issue with the thermostat. That code relates to the engine not getting up to temp fast enough. How is the heat in the car? If its been a little cooler than normal start with a thermostat. Alex

Right at the thermostat housing - (follow top radiator hose to engine) .. Unable to post images on this site. Keep in mind the coolant temperature sensor itself may or may not be the culprit!