How do you repair a gas gauge

Hi sharon2202,

There are three parts here to consider, the dial in the dash, the wiring between and the sender in the gas tank.

The most common failure is the sender, and the cure is generally to replace it. That means accessing the fuel pump retainer, which can either be in the trunk or under the rear seat, opening it up and removing the fuel pump, then replacing the sender. Here's a short page from Kia showing how to replace the fuel pump on an Optima.

Kia Optima: Removal - Fuel Pump. Repair procedures - Fuel Delivery System - Engine Control/Fuel System - Kia Optima TF 2011-2023 Service Manual

We would need to know what year your Kia is to give you an more specific information, including where to get the part for it; you can get the sender separately from the fuel pump, or buy a whole new fuel pump with the sender already installed. Obviously it'll be cheaper to just get the sender and replace it on the pump yourself, but you may have to figure out how to do that.

Less common issues would be a break in the wires connecting the sender to the dash gauge, which can be difficult to diagnose, and finally the gauge itself, which would involve removing the instrument panel and disassembling it to get to the gauge, but those failures are pretty rare; I'd definitely start with the sending unit in the gas tank.