This could of gone tot he grumpy old farts board, but I'm not grumpy to save $200.
My wife has a 2000 Subaru Outback and the service engine soon light came on.
Autozone offers a free diagnosis (plugs right in under the fuses), so I stopped by and found out the code, P0328 = Knock Sensor.
After researching all I could google on the code and knock sensor - the overwhelming remedy was to replace the knock sensor if the light continued to come on.
I called the dealer and told them what was happening and how much does it cost to resolve this. They quickly came back with $387 which includes an $87 diagnosis (that's the freebee at autozone)
My next question is how much is the part - they came back with $120. (they said this part is going like hot cakes since 10% ethanol came into play)
I bought the part and had my local mechanic replace it along with an oilchange and tire rotation for the tune of $66. replacing this part is 1 very accessibe screw and a plug.
Dealer = $387
non Dealer = $186 ( If got the part online it woulda been $156)