Q&A

a vacuum leak can sometimes be diagnosed by listening for the suction noise or use carb cleaner sprayed around the intake hoses, manifold etc and look for an rpm change or an oxy sensor change if you have a tester. this fault can be set for things other than a vacuum leak (like and exhaust leak or bad air mass reading) which are a little harder to diag. as far as brake lt sw fault, early audis set that fault if the brake pedal was not hit since the key was turned on. step on the brakes with the key on then check the fault. if its gone there is no problem.