Here you can find a fuel pressure sensor having a gauge and an alarm outlet pin:
See the calibration test result below.
The alarm sensor part switches on below 0,8 bar. (useful to lit "oil-pressure-too-low" indicator lamp)
Another type fuelpressure_sensor:
Its calibration curve is linear:
This is not absolute pressure, but relative to athmosperic. So 5bar measurement range means (1 bar athmosphere) + (for example):
- 2 bar boost + 3 bar fuel pressure (above MAP)
- or 1.2 bar boost + 3.8 bar fuel pressure (above MAP)