IIRC that sensor is on the side of the head. And as far as the coolant light flashing? Ours does that sometimes, and just a wee top up seems to settle it down (Even though it reads above the min mark). Like it was a mm low or something, and even a bit of heat expansion submerges the sensor. So siphon off some dehumidifier water, and see if a bit of added fluid fixes it. Cathy