What Do E and F on a Car Dashboard Gauge Actually Mean?
If you think that the āFā on your dashboard fuel gauge stands for āfullā while the āEā stands for empty, think again. Your car or truck is probably not empty when the needle hits āE.ā Most automakers build in a reserve of several gallons. In fact, some argue that the āEā actually stands for āemergency.ā
How does a fuel gauge work?
The fuel gauge in the dashboard of your car or truck shows the level of the fuel in your tank. The gauge accomplishes this by reading a float built into that tank.
When the automaker first assembled your vehicle, they installed a movable float in its gas tank. As the fuel level rises, so does the float. It moves a metal arm connected to an electronic resistor at the top of the tank, and varying the current sent to the gauge. This is why your fuel gauge moves from āFā to āEā as you burn gas.
But how full is āF?ā And is āEā actually empty? Automakers can actually calibrate how the gauge will communicate the float position, and may be using it to manipulate you.
See how your fuel gauge works for yourself in the video below:
What does āFā on my fuel gauge mean?
The āFā on your fuel gauge means āfull.ā When the float in your gasoline or diesel tank is at its highest position, the needle should be on or near the āF.ā
I know Iāve had vehicles that I could fill past āF.ā So if I topped off the tank, the needle would sit right at āFā for the next 50 miles, then start to pass through the rest of the gauge.
Depending on your fuel gauge calibration, āFā may actually mean a bit less fuel than full. But itās not critical that you know how precisely how full your tank is when you have plenty of gas to get home.
What does āEā on my fuel gauge mean?
Some say that the āEā on your fuel gauge means āempty,ā even though almost every vehicle still has a gallon or two of fuel reserve below āE.ā But others have claimed thatābecause the tank isnāt technically empty at āEāāthis letter truly stands for āemergency.ā
Most automakers calibrate their fuel gauge needles to land right on āEā a gallon or two before the tank is truly empty. There may be a few reasons for this, but they are all to help you out.
The first is the most obvious: If you are cutting it close, and running your car down to āE,ā having a gallon or two of extra fuel you donāt know about may be the difference between getting to the pump or stalling out stranded. Instead of an āEā some vehicles have an āRā for āreserve.ā But of course, knowing about this reserve makes it more likely that youāll push a tank further and run out of gas.
Secondly, just a slosh of fuel in the bottom of the tank may not be enough to get you to the pump. Most vehicles draw fuel out of the rear of their gas tank, so they are less likely to run out while climbing a hill. But this means that with a bit of gas left in the tank, you could stall out while driving down a hill. Itās a good idea not to run it down to the very bottom.
Finally, an older vehicle (weāre talking ten years, twenty years, or even older) may have some rust or other debris in its fuel tank. During normal operation, this litter may sink to the bottom of the tank and give you no trouble. But if you were to suck the final gallon or two out of your tank, this junk might clog up your fuel filter.
Most automotive journalists assume that the āEā on your fuel gauge means āemptyāāeven though this is an exaggeration. But the folks over at TotalEnergies.id argue that āEā stands for āemergencyā as in, āthis is an emergency, you are about to run out of fuel, get to a filling station.ā
Next, find out why you should run away from a used car with tape stuck to its dashboard or find out how far you can drive after your fuel gauge hits āEā in the video below: