Yeah, its the element inside the seat. This is alittle bit more of an expensive fix. Basically, the seat has to be taken apart(the leather has to be removed) and the heater pad replaced. It is definately something I would not recommend you do yourself, unless you know an upholstery guy that can remove and install the leather for you. If that is the case, you can buy the part, remove the seat, have the leather removed, replace the sensor, have leather reinstalled and put the seat back.
Ooh, also it could be a broken wire under the seat, but I don't think the light would come on at all if this was the case, but check just to make sure.
Let us know how it goes.
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