Vauxhall Vectra B - cam sensor - sparkarse

I have replaced both cam and crank sensors. The car is working fine, no problems except the management light stays on. I have cleared the code 0340, but it comes back on and stays on. Every now and then the light goes off and stays off til I use the car again. I put a diagnostic reader on and it tells me cam sensor 0340 signal not present intermittant. Has anyone had the same problem and some tips for me?

Edited by sparkarse on 13/09/2012 at 19:04