'''You're right you have a sensor issue. '''The sensor reports to the EFI that it can't detect/control the FAN so the EFI runs the fan at full throttle (by default in scenarios like this) to keep you from cooking your CPU.
I don't know if you damaged the connector, blew up the sensor but the error is basically saying it believes your FAN MOTOR (4MOT) for the HD (HDD) is out of spec. and the amount it's wrong is the last set of numbers in RPM (I suspect too slow - hence kicking it into overdrive).
MAYBE you need an EFI update to run that drive? What is it's SATA Speed (your bus is 3Gb/s Max)
Have you tried an SMC reset?
''If this answer is acceptable '''please remember to return and mark it'''.''