09 audi a4 gas gauge stuck at half full help
 

So my gas gauge has been stuck at half for a week and i was thinking it might be the sending unit but if it was the sending unit would it turn the check engine light on? I have read that adding some fuel treatment might help any suggestions?

so i added some more gas to see if maybe the float was stuck but when i turned it on the gauge still read half.

Not all issues turn on the MIL, and that assumes there's a mechanism in place to detect the issue. Scanning DTCs would be far more informative that if the MIL is on or off.
I don't know the mechanics of how the fuel gauge operates, but you could have a physically stuck gauge or a physically stuck float.

Service manual does discuss testing a connection with a multimeter.
Remove the rear seat bottom and the three screws round cover over the fuel pump. Unplug the bigger electrical connector. There should be five electrical contacts in the socket on the fuel pump top.

Fuel Level Sensor -G- Installed
– Connect the multimeter to measure the resistance between
contacts -2 and 3-.
• Fuel tank empty: approximately 60 Ω.
• Fuel tank full: approximately 275 Ω.
– Connect the multimeter to measure the resistance between
contacts -2 and 4-.
• Fuel tank empty: approximately 280 Ω.
• Fuel tank full: approximately 65 Ω.
– Connect the multimeter to measure the resistance between
contacts -3 and 4-.
• Arbitrary sensor position: approximately 340 Ω.


Fuel Level Sensor Removed
Note
♦ To check resistance values “tank full” or “tank empty”, the fuel
level sensor must be removed and the floater of the sensor
must be placed in upper or lower end position. Refer to
⇒ “5.3 Fuel Delivery Unit”, page 89 .
♦ With the fuel level sensor removed, the following values are
obtained because of the greater deflection of the floater arm:
– Connect the multimeter to measure the resistance between
contacts -2 and 3-.
• Sensor at lower stop: approximately 52 Ω.
• Sensor at upper stop: approximately 283 Ω.
– Connect the multimeter to measure the resistance between
contacts -2 and 4-.
• Sensor at lower stop: approximately 288 Ω.
• Sensor at upper stop: approximately 57 Ω.
– Connect the multimeter to measure the resistance between
contacts -3 and 4-.
• Arbitrary sensor position: approximately 340 Ω.
The fuel level sensor is faulty when the following is detected:
♦ Large deviations in measured values
♦ Measured value 0 Ω (short circuit).
♦ Measured value ∞ Ω (open circuit).
♦ No fault in the electric wires.


It looks like from the pic that you should see some text along the connector edge (EKP SENSOR EKP). If you look at it such that this text is above the connector (thus reading backwards), then the contacts are 1 through 5 left to right.

thanks my friend for the feedback i will lokk more into it