Symptoms of a Bad or Failing Fuel Gauge Sender

The fuel gauge sender is a component that is found in the gas tank of most road going vehicles. The fuel gauge sender, also commonly referred to as the fuel sending unit, is the component responsible for sending the signal that operates the fuel level gauge in the instrument cluster. The fuel sending unit is made up of an arm, float, and a resistor that changes according the position of the float. The sender float is designed to float on the surface of the fuel inside of the tank. As the level drops, the position of the arm and float will shift and move a resistor which controls the display on the gauge. When the fuel sending unit has an issue it can cause the vehicle to experience issues with the fuel gauge, which can put the vehicle at risk of running out of fuel. Usually a bad or failing fuel gauge sender will produce a few symptoms that can alert the driver of a potential issue.

1. Fuel gauge behaves erratically

One of the first symptoms of a problem with the fuel gauge sender is a fuel gauge that behaves erratically. A faulty fuel gauge sender may cause the gauge to suddenly change positions, or give an inaccurate reading. The gauge may appear to be at three quarters, and then only a few minutes later will change to half full, or vice versa the gauge may appear to be full, only to have the gauge climb higher a short while later.

2. Fuel gauge stuck on empty

Another common symptom of a faulty fuel gauge sender is a gauge that is stuck on empty. If the float somehow breaks or becomes separated from the arm it may cause the fuel gauge to malfunction and become stuck on empty. A faulty resistor can also cause the gauge to read empty.

3. Fuel gauge stuck on full

Another, less common, symptom of an issue with the fuel gauge sender is a fuel gauge that is stuck on full. A faulty fuel gauge resistor can send a bad signal to the instrument cluster which can cause the gauge to permanently read full. This is an issue, as the driver needs to know the accurate fuel level of the vehicle as to not run out of fuel.

The fuel sending unit is not a routinely serviced component, usually only serviced when it, or the fuel pump fails, however it does play an important role to the proper operation of the vehicle. If you fuel gauge is displaying any of the symptoms, or you suspect that there may be an issue with this unit, have the vehicle inspected by a professional technician, such as one from YourMechanic, to determine if the fuel gage sender should be replaced.


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Kenneth

20 years of experience
775 reviews
Kenneth
20 years of experience
BMW X5 L6-3.0L - Fuel System - Rancho Palos Verdes, California
Kenneth was extremely knowledgeable. He correctly diagnosed my vehicle by actually going under the hood, removing a section and running some sort of test that told him exactly what the problem was. He also arrived 15 minutes early and had prepared for the visit by contacting me the day prior to get further clarification.
Hyundai Accent - Oil Change - Los Angeles, California
He was friendly and efficient!

Chris

22 years of experience
2223 reviews
Chris
22 years of experience
Honda Element L4-2.4L - Pre-purchase Car Inspection - Laguna Beach, California
Chris was on time, thorough and I appreciated his candid opinion. He provided an extensive report including photo's and a verbal recording--more than I expected! Chris also followed up with a phone and answered all my questions. Well done, I would definitely use this service again and recommend it to others. Thanks
Toyota RAV4 - Check Engine Light is on - Huntington Beach, California
Always helpful, and awesome

Joel

21 years of experience
987 reviews
Joel
21 years of experience
Ford Five Hundred V6-3.0L - Spark Plugs - Jacksonville, Florida
Didn’t leave until it was fixed and doubled checked with good suggestions
Volkswagen GTI - Thermostat - Jacksonville, Florida
Joel is one of the best mechanic i've ever met. It was a great, fun and positive experience. Very knowledgeable, very professional, and he goes above and beyond. Not only that i will recommend him to my families and friends, i will recommend him to every person that need their car inspected or fixed.

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4 years of experience
230 reviews
Michael
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Volkswagen Jetta L5-2.5L - Fuel System Inspection - Indianapolis, Indiana
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