Everybody... thanks for this thread! We have 4 Subies - Wifes' 2006 Outback Wagon, My 2002 Impreza, Daughter's 2001 Forester, and Son's 1998 Legacy wagon. I had knock sensor go bad on Forester .. daughter replaced @ $125. I noticed CEL on in Impreza - dealer advised replacement cost $265! Forget about it! Went to Genuine site ordered part and thanks to you guys will replace over w/e @ 1/3 cost? You guys are like farmers .. outstanding in the field! Just have to learn about clearing ECM codes...