After scanning with Vagcom got the following DTS code for the Aux fuel tank:
00439 - Fuel Supply Sensor 3 (G237)
29-00 - Short to Ground
Wondering if it means the fuel pump is faulty and needs replacement or just wiring from-to the module?
After completely filling up the tank, the gauge stops nearly the top about 4/5. My guess is the auxiliary tank under the spare tire is not being filled up.