Audi tt mk1 P1639 fault
 

Hi guys got dreaded fault P1639
Garage have checked everything and all the wiring from pedal to ecu is fine and reading correctly. They've pinged all wiring from ecu all OK. They checked all plugs and all dry no corrosion. They everything wiring wise is fine. The only other thing tt hey said is it must be a dodgy pedal. The one I bought was part number 8N2721503A. But apparently the one I should of got was 1J2 721 503 J. They look exactly the same.
Fitted new pedal today and still got fault. Any ideas