[Fuel gauge/ Windows intermittent fsult]

Astra twintop 07 fuel gauge drops to zero and windows stop working intermittent then will come back on working all at same time 

[Fault code P0404]

Hi my insignia 2.0 cdti 158 (09) yesterday and the "service soon " appeared on the dash and went into lip mode pulled over and turned car off started again drove home about 5mins away plugged my scanner on and came up with P0404 any help would be appreciated Rob