knock sensor

have had my battery going flat on my Clio..RAC said it was likely to be the knock sensor/fuel cutoff sensor that was broken.
I have replaced it myself it as insructed by RAC but am concerned as the Haynes book suggests this shoud be done by a professional as if done wrong could cause engine damage.. it did seem quite straightforward.. any suggestions?

dont listen to haynes,that another way of saying go to dealers! where is the knock sensor exactly and what year clio is it?