This blog to be referred to once you have properly diagnosed a faulty crankshaft sensor (2005 - 2006 smart cdi) model only.
Follow the diagrams.
Note it was not an easy task but "NOTHING" else was needed to be removed in order to replace the crankshaft sensor.
A good flash light is a must.
You will also need to raise the rear of the vehicle to gain access from the bottom.
(If you are a shop and have a lift it will simplify things)