Fan Issue/Failed HD - 4SNA/1/40000000:TH00-9.000 Error - Need Help on Next Steps

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Fan Issue/Failed HD - 4SNA/1/40000000:TH00-9.000 Error - Need Help on Next Steps

I have an iMac (27-inch, Mid 2011), and the internal secondary hard drive failed. I have the primary drive which is a 250 GB SSD which is working fine, but I had secondary files and all back-ups on the failed drive (files are in iCloud so no issue - just mainly lost the backups). Since the drive when out, I tried the Drive Utility and ran First Aid, but nothing happened (it said done in about 1 nanosecond).

I ran Apple Diagnostics and got this error - 4SNA/1/40000000:TH00-9.000

Anyway, as I operate the iMac, the fan starts normal but then goes full tilt. I researched and found that that error is a thermal temperature issue.

Question - can I just remove that failed HD and would the issue likely go away? I can live without the secondary drive, and just plug in an external for backups. The fan issue didn't start UNTIL the HD failed. Or should I replace the thermal sensor? And if I have to replace the thermal, does it require another HD so that I should replace new HD to replace the failed one?

While I never opened the iMac other that to add more memory, I am proficient having built many PC's over the years - and did watch a youTube on how to replace a drive.

Other than the failed internal backup drive, the unit works fine (other than the noisy fan). I can manage fine with the 250GB as I have most everything in the cloud.

Thanks in advance.

iMac 27", macOS 10.13

Posted on Jul 19, 2019 11:45 AM

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Answer 1

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Pezmeister Author

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Jul 22, 2019 7:43 AM in response to Allan Jones

Allan,

I reset the SMC this morning - and so far, no fan running. The "dead" drive doesn't show up anywhere, which is fine. But resetting the SMC by unplugging it seemed too easy. I had previously shut down the iMac dozens of times to see if that would do anything (and help save the fan), but I would have never unplugged the machine. Do you recommend I do that periodically (unplug it?). I don't have the T2 Security chip, so unplugging it once it awhile is simple.

Off to buy a external drive for back-ups.

Thanks Allan and everyone who commented on this.

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Answer 2

Pezmeister Author

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Jul 20, 2019 7:33 AM in response to Allan Jones

Allan - no your suggestion was helpful.

I did type in the wrong error - you are correct, it is 4SNS

And yes, I purchased directly from Apple and added the secondary hard drive at purchase.

I've copied your answer below as I believe you deleted it, if anyone else has ideas.

Wondering about this:

While I never opened the iMac other that to add more memory...

Did you buy the computer with the second drive already installed? That model never shipped from Apple with two internal drives as far as my research has found. There are however aftermarket kits to allow replacing the optical drive with another HD or SSD.

Are you sure the code starts with "4SNA" and not "4SNS"? I don't have a code SNA for High Sierra.

If it is"SNS," then that code translates to a failed temperature sensor servicing the hard drive, NOT the hard drive. That would explain the high fan speeds. Codes for hard drive issues start with "4HDD."

On many iMac models you must add a special cable to maintain sensor function and quash spurious readings if you change the main hard drive. Example:

https://eshop.macsales.com/item/OWC/DIDIMACHDD11/

That said, have you done a SMC reset? That can help fan issues and is easy, so try it first:

How to reset the System Management Controller (SMC) on your Mac - Apple Support

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Answer 3

Pezmeister Author

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Jul 22, 2019 1:18 PM in response to Allan Jones

Thanks Allan,

In a bizarre twist, I rebooted earlier today and the "dead" drive came back to life, but the computer hung up when I tried to move one of the files from the bad drive over. When I restarted, it came up again with the message that a drive failed to initialize, and now I hear the fan running again.

I restarted the computer again after unplugging but I can hear the fan again - running...albeit at a normal speed (its been only 1/2 hour). It seems like the fan comes on when that drive somehow get's recognized, but it shows as uninitialized, and running first aid doesn't do anything. So it seems as though the drive might still run, but failing.

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Answer 4

Old Toad

Level 10

207,367 points

Jul 22, 2019 6:00 PM in response to Pezmeister

That model, iMac12,2 did come with two, non-Fusion driver installed as one option. I had a 256 SSD AND a 1 TB rotation drive in mine.

I had to remove the two drives when my graphic card crashed before I recycled it. The rotational drive wasn't too difficult to remove but the SSD was hidden under the motherboard and, for me, was impossible to remove in a manner that would let me reassemble the iMac sans drives. Since I was recycling the iMac thru Apple I just put everything in the iMac and snapped the screen back on (it's held with magnets).

If you can run OK with the fan app keeping the fan speed down then I suggest you try to do that and get an external hard drive for storage or backup. If you have patience and good at disassembly and reassembly then give it a try to remove the drive and replace the temp sensor. At my age I don't have the patience or steady hands to do that.

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Answer 5

QuickPost

Level 10

103,305 points

Jul 19, 2019 6:49 PM in response to Pezmeister

Hello,

My best guess would be that since the hard disk failed and newer Macintosh computer use the hard disk’s built-in temperature controller that when the hard disk failed the iMac is reacting to the fact it cannot read the drive’s temperature is assume it needs to ‘give it all she’s got’ to cool your system. My best recommendation would be to remove the failed hard disk (either yourself or have someone do it for you) in order to get things back to where they need to be.

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Answer 6

HWTech

Level 9

55,586 points

Jul 19, 2019 8:01 PM in response to Pezmeister

@zmclearan is correct about the problem. If you replace the drive or even remove it you would need to install a temperature sensor adapter cable so the fans don't run at full speed.

https://eshop.macsales.com/item/OWC/DIDIMACHDD11/

You might be able to use an app to control the fan speeds.

https://www.crystalidea.com/macs-fan-control

Working on an iMac can be difficult. The worst part is (dis)connecting the cables since you have just a tiny bit of room to reach in and visibility can be difficult. Usually reconnecting the LVDS cable is the worst since the cable and Logic Board connector are easily damaged. Sooner or later the internal drive may need to be removed if it begins to interfere with system performance or starts making noise.

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Answer 7

Pezmeister Author

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Jul 20, 2019 6:16 AM in response to QuickPost

That’s a great explanation and makes sense. Too bad I can just disable the drive without opening it up. I can buy a inexpensive external drive for backups. I may try the fan controller app below first. Thank you very much

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Answer 8

Allan Jones

Level 9

68,606 points

Jul 20, 2019 8:50 AM in response to Pezmeister

Thanks for commenting. I am the 4th slowest typist in North America and had to verify links. By the time I hit the "post button," other helpers had responded and I did not want to step on their toes!

Good to know the extra drive was an Apple BTO option. We web-ordered a 2011 iMac directly from Apple and I don't remember seeing that option. Maybe it was for the 27-inch models--ours is a 21.5. I take it a reseller did not add it before delivering it?

Try the SMC reset before doing much more.

Fan controller apps are worth a try but don't be too surprised if they don't help. The high fan speed you hear is a programmed system-level reaction to detection of a failed sensor and it may take priority over whatever a fan control program does. Still, several of the fan control programs are either free or have a trial period.

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Answer 9

Pezmeister Author

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Jul 20, 2019 10:13 AM in response to Allan Jones

Allan,

thanks, I’ll try the SMC reset, just verifying my type (after the Open).

And yes yes it was an option as back in the day of 2011, external drives weren't really an option. So I bought it fully loaded, and like I say, it works great until the drive failed.

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Answer 10

Allan Jones

Level 9

68,606 points

Jul 22, 2019 8:40 AM in response to Pezmeister

One hopes that you don't have to continue reseting the SMC. That would indicate an ongoing problem where the reset is the bandage, not the cure.

One note: I had some sleep issues with my 2017 5K and was not getting success with the SMC. Then I reread the instructions ("R-RTFM") and found I was not giving the appropriate amount of time off power and not waiting longer enough after replugging before restarting. Sounds like you did it right.

Did you add software or hardware, even externals, before this started?

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Answer 11

Pezmeister Author

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8 points

Jul 22, 2019 8:45 AM in response to Allan Jones

Allan,

No, I did not install the fan software, and left the failed drive in the unit. I have not added any software to the iMac recently. At this point, there isn't any benefit to opening and removing the drive from what I can tell. Thus, i will change my back-up to an external USB device once I purchase one.

Tom

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Answer 12

Pezmeister Author

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Jul 23, 2019 1:17 PM in response to Old Toad

OT,

Yes, my failing drive is the SATA 1 TB Fusion. Fan is running full tilt as we speak. What is strange, is that the drive comes back up yesterday, and now the symptoms is back. Allen above told me to do the SMC, and it worked, but when I restarted the computer, the drive came back up for a while and I could see both volumes; I have it split as Mac Harddrive 2 and Mac_Storage. I have since tried resetting the SMC (leave it unplugged), but that didn't work today.

When I start the iMac, I here a clicking noise, and then I know it's that drive. I get an error that it could not load that drive, and if I hit ignore, or eject, essentially nothing happens but when I run diskutility, you see the display above.

If the SATA is easy to remove, I may just end up doing that. But downloading that fan app now to try.

Thanks for the advice

Tom

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Answer 13

Old Toad

Level 10

207,367 points

Jul 23, 2019 5:03 PM in response to Pezmeister

Go to MacSales.com and check out their videos on replacing the HDD in that model. MacFixIt.com may also have some videos on what's involved.

It's easier than the SSD but one must be very fastidious, patient and organized so there's no screws or other parts left over. I'm lacking in all three areas when it comes to fixing.

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