Son bought a 03 Vw touran 1.6 fsi today, after leaving the showroom, about half a mile, a fault light came on, he returned to the car dealer and tested the electrics with his own dignostic meter and code P0328 came up, he re-set the code, travelled about 90 miles home, parked the car and about an hour later went out to do some shoping, light came on again, he belives it the knock sensor, the car is under 3 Months warranty and last week passed a full MOT with no problems, as he does not wish to travel the 90 miles back to the dealer can anyone help and explain the problem please, thanks.