I filled up my gas tank a week ago and has driven only 32 miles since then.While on 2000 Mercedes-Benz C230

driving yesterday the gauge went to empty as well as the gas warning light came on.Pulled over and shut off and re started the car gauge went to full again.Happened twice yesterday.Is this electrical or is thre a sending unit thats going bad?

Asked by for the 2000 Mercedes-Benz C230