after the AA put his diagnostic gear on the wifes car he found a fault with the camshaft position sensor, the engine lights been on the car ever since we've owned it, and the main dealer just reset it every time they serviced it only for it to come on after a few days, they said it was nothing to worry about and the car has always ran fine, has anybody replaced this sensor or had it done and what sort of price are we talking. It looks quite easy to replace according to the haynes manual.