cpm sensor?

Hi my my 2003 micra is giving me trouble in the mornings starting. Not a battery problem. Got a car diagnostic test done and came back with cpm sensor problem. Few questions, firstly how much will this be to get replaced? Big Job?. Would this be the reason the engine isnt starting? Its starting ok, then cuts out, start it again, give it a few revs and off we go! Starts for the rest of the day no problem. just want to get a rough guide on what i should be charged. Thanks a mil.

Had a similar problem recently,turned out to be the alternator,maybe you should get that checked,if it is you can pick up one in a breakers for 60 to 80 euro, shouldn't be more than 50 to fit it