well according to the serial number you gave it's not a good number or is too old and is not in hyster's db. comes up as a bad number.

but based on the truck model i can guess this has a curtis controller in it? GE control codes are not in this format.
according to curtis that A5 01 could be a 501A which is listed in curtis's code list and is shown to be a steering control code.

MDU Prox Steer: Feedback sensor error.
it says to check MDU proximity sensor and wiring.