Code P1623, Prom Error
WARNING: This page is about a different car, the 1994 Oldsmobile Ninety-Eight and 1994 Buick Park Avenue. However, it is still accessible from the selected car via links, so may be relevant.
Check that PROM is correctly inserted in the socket. If okay, replace PROM, clear memory and recheck. If Code P1623 reappears, replace PCM.
NOTE:
To prevent possible electrostatic discharge damage to PCM or PROM, DO NOT
touch component leads. DO NOT
remove integrated circuit from carrier.