i have a 96 gsr with a jdm b18c swap. i was running with a jdm 98' p73 ecu until i failed emissions (illinois emission law is just an obd check for 96+ cars) because their computer couldn't connect to my ecu.

i went back to the stock p72 a02 ecu. CEL light goes on and throws code 54 CKF - crank fluctuation sensor [P1337 Engine Speed (RPM) Fluctuation Sensor No Signal]. to my understanding (due to what i have read), my engine is missing the Crank Speed Fluctuation sensor on the oil pump (please correct me if im wrong) so my questions are as follows..

1. is there anyway to get around this besides installing a crank sensor?
2. how do i fix the problem?

thank you for your time.