Is there anything I can do about my inaccurate fuel gauge? Today it was at the bottom of the red zone, and I put in 9.5 litres and it went up to half a tank, but the tank is 42 litres.

I have an OPCOM device, but I don't know how to read the actual amount of fuel in the tank.

Is there anything I can do to fix this?

2003 Opel Agila

  • Assuming your Agila has a floar-style fuel level sensor, I'd inspect the fuel level sensor for any obstructions that may be causing the float to bind or stick.
    – Zaid
    Dec 17, 2015 at 21:10
  • Did you buy this vehicle new? If so, has this issue always existed since day 1 or did you just notice it? Dec 17, 2015 at 22:41
  • Is this new behavior or something which has been there and irritates you? The 4th gen Camaro is notorious for doing the same thing. The top half of the gauge would last you for 300 miles while the bottom half would get you about 80 (guessing at the numbers, but it was start, to say the least). You'd get down to a 1/4 tank and you better start looking for a fueling station! Dec 18, 2015 at 3:50
  • 1
    Quite a few level sensor systems are only designed to be accurate at full and empty. Levels in the middle are "suggestions". Dec 18, 2015 at 6:13
  • I've only noticed recently, as whenever I put in about 10 litres from empty, the gauge goes up to 1/2
    – George
    Dec 21, 2015 at 19:05

1 Answer 1


The float lever in your fuel sending unit may have a built up residue on it preventing the float from rising and falling properly. I believe your vehicle has an internal fuel sending unit within the fuel tank. and I believe that your access point for this fuel sending unit is from within the vehicle under the rear seat. This float lever on your fuel pump assembly can be cleaned or moved by hand (up and down) to help break up any residue that may be hindering it's movement. In this case you only need to fiddle with the float and nothing else. This information is based only on the information you gave about your fuel guage and not about your fuel flow. there is a bolt in the center and behind your back seat. remove that bolt to remove the seat. unscrew the fuel unit shield, disconnect electrical connectors & fuel lines. remove the sending units mounting screws or bolts and slowly pull the unit up and out far enough so that you can reach the float and just start playing with it to gain free movement and then re-install in reverse order.

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