The check engine light has come on and the computer at Auto Zone suggests the engine coolant temperature sensor needs to be replaced. The computer also suggested the thermostat could be bad, but I don't think so. The coolant level is OK. The car is not overheating or running too cold. No trouble starting when cold. The Temp gauge in the dash is right in the middle of the range, where it has always been. As far as I can tell, replacing the sensor should be relatively easy. But, we can't locate in on the car. Any help, including diagrams would be appreciated.