If it use the same injector as the B5 from what i read is the Piezo valve wiring is what normally fails.
The piezo socket on the injector has TWO pins.
Neither should be connected to the casing (Earth or “-“).
Set your multimeter to continuity or Ohms.
Place one probe on one connector pin and the other probe on the injector body.
The meter should read “1” and not buzz.
Repeat for the other connector pin. If the Piezo valve has failed the meter will buzz or give a reading. A failed injector will give a reading of 400 – 500 Ohms or less.
Or you could run some diesel purge thru it.