For the last few months everytime my car's gas guage hits around 3/4 of a tank, the needle drops to around 1/4 or less and stays there until enough gas is used so that the reading is less then 3/4 full. When the reading is less then 3/4 the fuel guage reads correctly. I have used a code scanner and no codes came up.

 

Sante Fe's in those years have fuel sender issues.If you want to tackle it yourself well you can replace both.From a technician point of view.We can remove senders and inspect resistance and replace the failed one.You might want to think about this.