Don't know about the 2001 model, but my 2000 with 179,000 miles on it has been doing that for a while. The first couple times I took it to the Subaru dealer, and they charged $90 to turn the damn check engine light off. It started coming on and off again this summer and fall and has been on steady for the last couple months or so. I fixed it using the advice given by Click and Clack on Car Talk. I put a piece of black electrical tape over it, and it's been just fine. Much cheaper and works just as well as the shop solution.