Why does refueling without turning off the engine cause the fuel gauge to be inaccurate?

[ReidDella]

Due to the presence of many impurities in gasoline, the fuel level sensor, which is constantly immersed in it, can become contaminated over time, directly affecting the accuracy of the readings. The following are reasons for inaccurate fuel gauge readings: 1. Fuel level sensor issues: The fuel level sensor may have poor reliability or be damaged. 2. Problems with the fuel gauge: If the fuel gauge needle drops at inconsistent rates, it could be a design issue. Some vehicle models' fuel gauges are not designed linearly, with the first half being slower and the second half faster, which is relatively normal. An unstable fuel gauge needle may indicate an issue with the fuel level sensor. If the fuel gauge needle does not reach the top after confirming a full tank, there may be a problem with the fuel gauge display.

[MiguelAnn]

Refueling without turning off the engine can indeed cause the fuel gauge to be inaccurate, mainly because the fuel pump remains operational while the engine is running. It continuously pumps fuel, leading to significant fluctuations in the fuel level inside the tank, which interferes with the fuel level sensor. The sensor is designed to display readings based on static fuel levels, but with the engine running, the fuel sloshes around, causing the sensor to misjudge the actual amount. I remember one time I forgot to turn off the engine while refueling, and after leaving the gas station, the gauge still showed half a tank when it was actually nearly empty—scared me into pulling over to check. Now, I always remember to turn off the engine when refueling, and the gauge is much more accurate. It’s also safer, as refueling with the engine running increases the risk of fuel vaporization and potential explosions—definitely not worth the risk just to save a little time. Regular maintenance checks on the fuel gauge system can also help prevent this issue, so small problems don’t turn into major repairs.

[VanNatalie]

Refueling without turning off the engine can cause the fuel gauge to be inaccurate. I've looked into the technical reasons behind this. When the engine is running, the fuel pump is continuously operating, drawing fuel from the tank to supply the engine. This process creates unstable fuel pressure inside the tank. The fuel gauge sensor relies on a float or conductive plate to measure fuel level, but in a dynamic state, the float can fluctuate with the fuel surface, leading to incorrect readings. Simply put, when the car is running, the fuel level is dynamic, but the sensor assumes it's static, resulting in display deviations. To test this, I've tried restarting the car immediately after refueling, which helps. However, if this issue occurs frequently, it might indicate an aging sensor that needs replacement. In daily use, developing the habit of turning off the engine is advisable—it's safer, more fuel-efficient, and extends component lifespan. Don't overlook these small details; they help prolong your car's service life.

[BrandonFitz]

An inaccurate fuel gauge is likely due to not turning off the engine while refueling. I encountered this issue with my family car—fueling with the engine running kept the fuel pump working, causing the fuel level reading to fluctuate and display inaccurately. After the incident, I drove back to the gas station, where the mechanic explained that the fuel gauge would return to normal once the engine was off and the fuel level stabilized, but doing this repeatedly wastes fuel. So, I remind everyone to always turn off the engine before refueling. It's a simple operation that saves hassle and effort. Developing this habit can also reduce vehicle wear and extend its lifespan, saving you unnecessary expenses in the long run.