replaced the crankshaft sensor on my '06 159 last night, what a job!
it took a little over 2 hours, i shall tell you my findings!
use an old blanket or similar to "pad" the top of the engine, as it is not very comfortable to lie on.
remove the fuel filter and bracket from behind the engine, this gives you a few more inches to play with.
make sure you have long torx bits, (like an allen key set, not socket types) as they are needed to get into the securing screw.
keep referring to the new sensor to make sure you are pulling things the right way!
the sensor is located directly underneath the starter motor, a pain in the a** to get to!
once you have located the sensor, removed the electrical connection and loosened the securing screw, the actual changing of the sensor and finishing the job from now on isn't too bad.
disconnect the battery negative, (as you are near the starter motor and working "blind")
if you have any other questions then please just ask me and i will do what i can.