DTC P1988-00: OPU (Oil Pump Control Unit) Signal Circuit Fault: General Description
WARNING: This page is about a different car, the 2024 Kia Sorento. However, it is still accessible from the selected car via links, so may be relevant.
Electric Oil Pump (EOP) provides hydraulic pressure to engage and release clutch/brake of the transmission. It supplies ATF or generates hydraulic pressure in all sector (always active after start-up).
Oil Pump Unit (OPU) is controlled so that EOP can supply the oil flow to the transmission properly.