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Q: I have a 2000 Buick Century and the gas gauge goes up and down

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The gas guage is intermittently. I'll start the car up and it'll instantly go to full. Once I'm driving it'll go back down. I'll have a quarter tank and while driving it'll go between empty and a quarter tank. The gas light will come on a few times but once I step on the gas pedal the gauge will go back up. It's really funky. Could it need a fuel gauge sender replacement?

My car has 140 miles.
My car has an automatic transmission.

A: You’re guess of the fuel sending unit is a ...

You’re guess of the fuel sending unit is a good one. The sending unit is a variable resistor, that changes its internal resistance according to fuel level. This information is then sent as an input to the powertrain control module (PCM), which shares this it with the instrument cluster over the communication bus. The sending unit is part of the fuel pump and the two must be replaced as a unit. To determine for certain whether the sending unit is at fault, I recommend having your vehicle’s gauge inspected firsthand by a professional.

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