Turbo underboost on VW — on 1.4 TSI and 2.0 TFSI it's commonly the wastegate actuator; on 2.0 TDI it's the N75 valve or VGT actuator.
Bob's Mechanical Repairs — independent family-run garage in Birnam, Dunkeld, Perthshire. Call 01350 727 276 or email [email protected].