Many pressure and level sensors used to be a variable resister type principle.
The supply was 5v from the relevant control unit.
Most of these have been replaced move with variable capacitor or hall effect sensors.
However the supply and output remains the same.
Supply 5v and output 0.5-4.5v
0.5v on a pressure sensor would equal 0 pressure and 4.5v as a maximum output.
Click on the variable resister and move the Yellow Triangle (Resistance adjustment) from 90%=0.5v output to 10% =4.5v output.
