01 / GUIDE
The reference changes the meaning
Absolute pressure is referenced to vacuum. Gauge pressure is referenced to the local atmospheric pressure. A value expressed in psia is absolute pressure and should not be read as the same amount of boost above atmosphere.
02 / GUIDE
Use the right conversion
At a given atmospheric pressure, gauge pressure equals absolute pressure minus atmospheric pressure. Local conditions matter; the two ratings should not be compared without their reference and units.
03 / GUIDE
A name is not a calibration
A model name such as “4.0 MAP” does not by itself establish the range, voltage curve or pressure reference. Check the exact part number, sensor supply, signal output and calibration expected by the ECU.
Checklist & example
- Example only: 200 kPa absolute at 100 kPa ambient means 100 kPa gauge.
- This arithmetic is not a sensor rating. Use the actual local ambient pressure and the sensor calibration.
