Wrongly charged for diagnostic test? My VW Golf GT Sport TDI is three and a half years old. The ABS light came on and I took it to my garage for a diagnostic test: £170 later I was told it was the ABS controller unit. Is this a common fault and what do you suggest? It's probably the brake pressure sensor in the electronic stability program module. A repair costs £225 at www.sinspeed.co.uk, plus the price of removal and fitting. If I'm correct, you did not need to pay £170 to find that out and should demand a refund.