P1648-vw

The transmission or braking module itself is failing to communicate.

The Volkswagen fault code is a specific powertrain error indicating a Data Bus Powertrain Malfunction . This code typically means the Engine Control Module (ECM) is not receiving or is receiving corrupted information from another critical module—most commonly the Transmission Control Module (TCM) or ABS module—via the CAN Bus system. Deep Dive: P1648/18056 – Data Bus Powertrain Malfunction VAG Code: 18056 p1648-vw

If water ingress is minor, cleaning the connections and drying the module can solve the issue, though the water leak (usually clogged sunroof drains) must be fixed. The transmission or braking module itself is failing