You have driven 300 miles and the gauge still says full. Eventually you run out of gas because you cannot trust it. Almost always a stuck float or shorted sender, here is how to confirm and fix it.
The float arm jams in the full position, often from rust or debris in the tank. The gauge stays pinned at F until you replace or free the sender.
Get a full diagnosis →A short in the rheostat shows zero resistance, which the cluster reads as full. Common as the unit ages and ethanol eats the contacts.
Get a full diagnosis →A signal wire shorted to ground (from chafing or rodent damage) gives the same reading as a shorted sender, full.
Get a full diagnosis →Bad gauge driver in the cluster pins the needle high. Look for other dash quirks like a stuck temp gauge.
Get a full diagnosis →On newer cars the body control module reads the sender and feeds the cluster. A software glitch or weak power can stick the value. A battery disconnect often resets it temporarily.
Get a full diagnosis →| What You Notice | What It Usually Means |
|---|---|
| Gauge pinned at full | Stuck float or shorted sender |
| Light comes on but gauge says full | Conflicting low-fuel sensor working, main sender dead |
| Reading flickers between full and accurate | Intermittent short or loose connector |
| Gauge resets after disconnect, then stays pinned | BCM software issue |
| Fuel mileage suddenly seems wrong | Stuck gauge masking real consumption |
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If your scanner is showing one of these, that's your starting point. Tap any code for full causes and repair costs.
Sometimes a stuck float frees up after a sharp brake or hot day. But once a sender goes, it is almost always going for good.
Yes if you track miles. The bigger risk is running out and damaging the fuel pump, which is much more expensive than a sender.
Yes. Fuel cools and lubricates the pump. Running it dry, especially repeatedly, shortens its life. Modern pumps cost $400-$900 installed.
Intermittent short, usually a chafed wire making contact when the suspension flexes. Inspect the harness near the fuel tank.
Sender replacement: $250-$600 installed. Cluster repair: $300-$700. Wiring: $50-$300. Diagnose first or you will pay twice.
Pump and sender share an assembly on most cars, so if you replace the pump, you usually get a new sender too. But a pump issue alone does not stick the gauge.
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