If it works, you can't fix it!
Monitor & look for other symptoms.
Temp/oil/Alternator
Do you think the whining noise triggered the Limp mode?
Does water, rain, or a car wash play a factor?
Does the whining sound the same with the HVAC on or off?
Doe's the whining sound frequency change with RPM's?
Is there a whining sound, when you turn the wheels left or right?