Nevell

Ok the car drives fine when I give it proper welly the cell light comes on and stays on but the car still drives fine .

I have done a lot of research on this and have found out about bugeyes and cel lights lol lol ahhhhhh

Well I know it's not the nps sensor that is common because this was changed last year on service records
And tere is no codes for misfires I have a code on my memoscan (good bit of kit)

Po340 generic camshaft position sensor a-bank 1 circuit malfunction

, now is this the sensor under the oil dipstick going into the cam cover on top of the engine ??? This only happens on very high revs I have heard that this can also be down to a bad earth?? If so what earths do I check, I've also read that subaru made a bad batch of these?
And are the £24 camshaft sensors on eBay any good for the job because subaru want 120 for oem , sorry so many questions I have erased the code only happens if I give it the beans but drives fine any help would be appreciated ....