Chosen Solution
I put a 2T HD hybrid and downloaded fan software work great for about 2 months then Gray screen ran D test came up with 4sns/1/40000000:th00-9.000 , what to do, can this be fixed by installing 2nd market sensor like, OWC, https://www.youtube.com/watch?v=Z7logpha…
This is a clear and 100% effective solution for all iMacs with 4SNS/1/40000000:TH00-9.000 problem after replacing a HDD: https://www.elvikom.pl/imac-21-5-27-blad… Please note that Macs Fan Control DOESN’T solve the problem because you still have an error in Apple Hardware Test! Macs Fan Control does only control fan speeds and has nothing to do with a HDD temperature sensor detection. My solution resolves all the issues after HDD replacing, like:
- Mac OS runs very slow,
- fans are running at the maximum speed,
- kernel task is equal or above 100% in Activity Monitor,
- AHT and ASD are reporting TH00 temperature sensor error.
That is the exact product you need, because that error code is for the HD Thermal sensor. Though I’ve never seen the grey screen problem before, let us know if installing that sensor fixes it.
Hi again Lucas, Part of my message has disappeared from the last post.. After applying your fix all the data on the HDD was gone. My iMac requested a new Initialization of the HDD. I therefore removed your fix and I could again access my HDD data, and of course the initial Error came back. Do you know if this fix requires a new initialization of the HDD?
