I noticed this recently with newer cars with electronic displays, in that for whatever reason, if you only add a gallon or two of gas, the fuel gauge won't update. However, if you fill it from a quarter tank to full, it will get adjusted accordingly.

Why do they act like this? I had assumed that they were measuring the volume filled of the tank itself, but then why would a gallon or two of gas not update at all?


That is down to the resolution or accuracy of the sensors used.

To consider an “old” example, the sensor was a variable resistor with the float moving the wiper across the resistor. Had a customer who was not happy with the poor gauge reading - and so we re-wound the resistor so it was a better indication of the fuel level.

Some sensors are now a set of switches in a tube operated by a magnet - so cheap is paramount and the number of switches controls the resolution.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.