How do you change a knock sensor on a 1999 Subaru Legacy Outback?

ALL Subaru knock sensors are: 1) in the same place 2) look the same The knock sensor is always found mounted to the engine block (12mm head on bolt) under the intake manifold in about the middle of the engine. Either being a Bosch unit, or a copy made under licence, they all appear to be the same: http://rb-k.bosch.de/en/start/sensorik/kopfsensor.html Being the one with the moulded-in leads. Locate the wiring in the vacinity of the throttle body and follow it down to the knock sensor. Changing one needs about $100 worth of tools, small hands, and LOTS of patience. They are expensive, be warned, before you buy check the thing with a volt-ohm meter, typical resistence is 300-500 ohms.