renault megane cam sensor problem?

i have bought a renault megane 04 1.6 2 door and it has not run properly since!
stalling too easilly when low speed manovering with the lights diming under engine load no engine management lights on but codes for cam sensor on diagnostic, seems not covered on warranty is this a comon fault what should i do next could b a good car but real pain only 23000 miles now was 17000 when bought please help

dave williams
August 2008