Looking for some help on irish fuel gauge

Just bought 54 plate fabia classic 1.2 and the fuel reading is reading full when empty and empty when full.....

Not really done enough miles in it as just a wee runabout 2nd car to see if runs up when getting low on fuel.....

cheers

Maybe had a new sender or something and its wired backwards?? Sure someone will come along and give a definitive answer

Without looking at it,I dont think it is possible to 'wire the sender backwards' because one side may be connected to ground,or the plug connecting it is 'keyed',and cannot be put in 180 degrees wrong.