We use Garmin's product too and haven't encountered any problem with it.

Ok thank you for your answer. I sent a mail to Diamond Austria about it.
Do you know if Diamond already talked about this issue ?

Hello and a happy new year to everybody. We are flying a brand new DA42-VI (came out of diamond factory in november 2017, less than 100h) and we got some problems with the fuel gauges. In fact we fly 1h45 to 2h flights with full primary tanks (50 usg), on the ground the fuel gauges indicate 25 usg i...

Hi all,
I the fuel system the same on the VI and the TDI ? I am also going for FlyingShrink's guess. One tank may be cross feeding the other.
Malcolm