P1648-vw Page

If internal module damage is diagnosed. If you can provide: The exact vehicle year and model (e.g., 2004 Passat 1.8T). Any other fault codes (e.g., P1626, ABS codes). If the ABS or Transmission light is on.

Water entering the TCM enclosure (often located under the carpet on the passenger side in Passats/Audis) causes severe corrosion and communication failure. p1648-vw

Pull up the passenger-side carpet/sill panel, open the TCM plastic box, and look for water, condensation, or green corrosion on the pins. If internal module damage is diagnosed