need advice please engine check light on again
 

hi guys, had a 2002 wrx bugeye around 3 weeks, last week engine check light came on then went off, so as its a new car, off i go to subaru main dealer for a plug in, 197 notes later its had a new cam sensor and the ecu reset, been fine for a week then today its come on again, so the questions are will this be a new fault??= more money or should they have sortyed it?? problem is i love the car so want it right, also can i trust a subaru main dealer as i know zero about imprezas and they could just tell me anything and i dont wanna be spending 197 a week on diognostic check plus sensor etc labour!! just want to know what you thinks the best thing to etc.. advice much appreciated...thanks in advance