hi tasci,
the pressure sensor got the order number 1831887. it comes fully calibrated and is easy to change.
you can check the bargraph like this:
-locate the connector X1
-connect pin 5 + 6 to 15V an pin 1, 2, 3, 4 to GND (or just let the connector connected to the board, so the right voltages will be supplied by the board)
-if you now connect pin 10 - 19 to GND, the correlating LED's (V15 - V24) have to lit.
if that works your bargraph is okay and maybe the driver is defect.