P1648-vw -

Verify the ECM and TCM are receiving proper voltage and have good grounds.

I can help identify the most likely culprit and direct you to the specific module to check. VW P1648 Code: Troubleshooting and Solutions | JustAnswer p1648-vw

Broken, shorted, or corroded wiring in the powertrain CAN bus network. Verify the ECM and TCM are receiving proper

Check for accompanying codes like P1626 (missing message from TCM) or ABS/TC-related codes. p1648-vw