My gas gage is stopping at half a tank lately and not going under half even when gas is being used. My question is, will the E light go on if the needle on the gage does not make it to E, or does the light go on when a sensor in the tank tells it to?
Heck my empty light comes on all the time, except when I am down to the last two gallons, then it turns off.
As for you specific question, I would not count on it. I would suggest getting it fixed, or refill shortly after it comes on even if you think it has lots of fuel left.
Usually, but not always, the low fuel idiot light is driven by a different sensor. To answer for certain one would have to know what make and model of car you have.
Carry a gallon of “emergency” gasoline and stay out of situations which would be exceptionally hazardous to run out of fuel, and run out of fuel. Or try to. See for yourself if the light comes on before the engine quits.
Another thing you can do to live with the situation would be to reset your trip odometer every time you buy a full tank of fuel. You’ll learn how many miles per tank and can judge fuel level with the trip odometer.
2001 Saturn L200 - weird that this was entered before posting but does not show up …
Good tip about the odometer, thanks. So obvious! It has also ‘clicked’ the fuel pumps off when refueling even though the tank is not full, so I’m sure there is an issue with a sensor someplace.
The fuel gauge on my 2000 Blazer quit working a few years ago. The only time the low fuel has come on since was just before the truck ran out of gas (forgot to fill up the tank). GM vehicle of this period has a problem with sulfur contamination of the sending unit.
I track the mileage and try to refuel with 3 gallons (out of 18) left in the tank. That works out to about 240 miles in cold weather and 255-270 miles in the summer. The 3 gallon mark leaves an ample reserve.
The instrument panel in my '05 Mustang went haywire causing my fuel gauge, temp. gauge, and speedometer (says I’m going 120 mph when I’m going 50, etc. - problem temporarily solved by using the speedometer on my GPS) to go out. I have heard this is a common issue with my vehicle (and an astronomically expensive fix, if you take it to the dealer) and due to stepper motors that drive the various gauges. My idiot low fuel light DOES work, however, and I know at about 250mi on the trip odometer, it is time to get fuel (I generally get to around 315mi until the idiot light comes on, but I don’t like to push it).
Be careful with the odometer trick. You need to figure out how far your car can go on a tank of gas, and then add a generous margin of error. Keep in mind, if you sit in traffic a lot, you will use more gas for the same mileage than you would if you were driving in uncongested traffic. For example, if your car gets 30 MPGs and has a 10 gallon tank, it should be able to go about 300 miles between fill-ups. However, if your fuel economy declines because of a mechanical problem, or because you sat in rush hour traffic on a couple bad days, you might run out of fuel after 250 miles instead of 300. In this case, I would simply fill-up every 200 miles.
I will also caution you to make sure the odometer still functions properly. Often, when the speedometer stops working, the odometer also stops working.