Check the connector
It may be loose or corroded. It should drop to 1 bar or lower at idle when warm. Varies from car to car. With an open circuit, it will go full scale. Sending unit is on drivers side of the sump.
2000 Dodge Grand Caravan SE
No matter what you fix, there will always be something else to fix..
"Warranty" is just another way of postponing the inevitable.