oil indicator

friends 2003 206 hdi, after turning on the ignition, there is a box with a box indicating the mileage first and then the oil level. The oil of the vehicle is not even missing, but the level is completely single line. I wonder if the oil does not go to the engine or does it show as it is too much oil.

the oil level sensor may be defective, my teacher will go to the engine if the oil does not go to the engine.