It's on the passenger side of my Mar 05 build E46 Coupé if that helps. If you cannot find the plug, then the plug is still connected to the temp sensor lying by the side of a road someplace. All is not lost, its a common enough problem. Simply get a replacement plug splice it to the wiring left behind (2 small wires) and plug it back in. However this time, don't use the location in the archliner/splash guard on its own..secure it firmly (and loose wiring) with some cable ties. Mine's had no troubles since and is still firmly in place.