Other answers are good but I found it almost impossible to see. It was there though. It might be easier to follw the wire to it. The sensor is held in with one bolt which can be accessed from above, but seeing it is awful!
It is underneath the intake manifold. If you look straight down from your throttle body, you will see a sensor with one wire coming out and a bolt going through the middle of it, that is the knock sensor.
Knock First - 2003 Brittany M- 2-25 was released on: USA: 2004
Knock First - 2003 Jeff A 1-1 was released on: USA: 25 September 2003
The EPA mileage estimate for the 2003 Subaru Legacy is 18 mpg in the city, 25 mpg on the highway.
The EPA mileage estimate for the 2003 Subaru Impreza is 19 mpg in the city, 25 mpg on the highway.
The EPA mileage estimate for the 2003 Subaru Outback is 18 mpg in the city, 25 mpg on the highway.
The EPA mileage estimate for the 2003 Subaru Forester is 19 mpg in the city, 25 mpg on the highway.
Knock First - 2003 Celebrity Edition Kimberley Locke 2-99 was released on: USA: 25 February 2005
its located under the head on the drivers side you can buy the wire separate 25 bucks the head has to be removed
He and She - 1967 Knock Knock Who's There Fernando Fernando Who 1-25 was released on: USA: 6 March 1968
Knock on the Sky was created on 2002-06-25.
Knock Knock - 1940 was released on: USA: 25 November 1940 Denmark: 30 November 1953