where is my speedo sensor on car?

i have a renault kangoo 1.5 dci 2003 i think the speedo sensor is knackered as it not working and the car when in 2nd keeps chugging as if in to high a gear put foot down a bit and it stops but speedo still no good, is it the sensor? and if so where is it and how do i get to it? thanks

andy 2
January 2012