On my E-420, occasionally when I am at a stop light I hear a loud whirring/chattering sound from under the hood. I was finally able to diagnose the part that is producing this sound. The part looks like a sensor and has a socket on top into which an electric connector plugs in. It says "MOT" on top of the part and it has two tubes coming out from either side. It is located on the driver side and under normal conditions it gives a pulsating vibration when you touch it. Can anyone tell me what this part is called so that I can replace it? Thanks.