stuff breaks !!! being a divability specialest a ford dealership i have replaced alot of DPFEs it is a common problem on al makes dont condim ford for it and i dont know why you asked how it worked because u hit the nail pretty close to the head and if your pretty handy with tools u could have fixed it yourself all u needed was a 1/4 inch 5.5 deep socket and a 1/4 inch ratchet there is only 2 bolts and its prety easy to get to thats if its a 94-98 but on a 99 and up i could do it blind folded dissconect the connecter unplug to hoses replace sensor and reassemble but u couldnt clear the code unless u had a compatable scan tool at hand what code did u get a P0401 ???