On a 3 wire sensor ( Pressure transducer ) most of them work like this. .5V = 0 psi 4.5V = 500PSI the 500 PSI and 4V range is linear. Each .1 volt = 12.5 PSI. Example, 1.8 volts = 13 x 12.5 That’s 162.5 PSI Remember .5 is 0. If they are not defective, they are... Login to read more.