AHT error: 4MOT/4/40000003: HDD-1255

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Level 1

8 points

AHT error: 4MOT/4/40000003: HDD-1255

Hi everyone, I had some troubles with my iMac lately. The computer freezes and a "snow pixel" appears. First i thought it was de grpahic card or something. That day I tried EVERYTHING, reset the PRAM, entering on single user mode and doing the fsck thing, I tried to re install de OS and nothing, after an hour (aprox) of many many tries I was about tu run de Apple Hardware Test and wen I restart the mac magically started like it was never happened nothing to it!!

It worked fine for 2 days, but today I started it and open an app and do the same thing, freezes and that annoying "snow pixel" came out. I tried again doing some things as the fsck thing, trying to enter in safe mood (don't worked) and reseting de PRAM and nothing... and insertede de DVD to do the AHT.

It started but with the "snow pixel" still, i do the test and the first time the result was: 4MOT/4/40000003: HDD-1239 and I freak out, then I do the test again but in the "extended" version and the result was this code: 4MOT/4/40000003: HDD-1255

I don't know what this means and I'm freakin out about it, if someone has some idea please feel free to speak it.

(I upload some pictures of what was happening with de "snow pixel")

I had OS Mavericks, but originally the iMac had Snow Leopard

iMac, OS X Mavericks (10.9.5)

Posted on May 2, 2015 2:16 AM

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Answer 1

K Shaffer

Level 8

35,002 points

May 2, 2015 2:42 AM in response to bnl18

From the results of a few searches online, the AHT error appears to mean this:

4MOT (motor) & some suggest that would be a fan issue, perhaps cooling HDD.

However there may be more than one thing going on in the computer and you

may see if an Apple Store with Genius bar could help diagnose similar results

and give you their take on the meaning of these codes. Appointments usually

are necessary, and even if the computer no longer has Applecare coverage,

you usually can get some help and an idea what's going on. If no Apple Store

(with genius bar) you may need to try an Apple Authorized Service Provider.

Or check around for an Apple Specialist. You'd likely pay for diagnostics, then.

Sometimes if there's excessive dust in the computer, it may show things are

acting up, such as overheating; or fan failure, cooling issues, etc. Or a hard

disk drive that may be running hot or on its last legs & needing replaced.

The error indicates a hardware cause, so this may be a symptom of pending failure.

But the temperature sensors may be acting up, if this relates, and the margin of

error for them may be compromised if there is dust inside affecting cooling efficiency.

Without knowing for sure, the exact build model iMac, can't say if there may be

another issue going on to contribute to the Error message. Or if there had been

a EFI firmware update for that computer, still in existence, that may apply. Given

the age and wear, an earlier iMac may need a replacement hard disk drive by now.

In any event...

Good luck & happy computing! 🙂

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Answer 2

bnl18 Author

Level 1

8 points

May 2, 2015 1:05 PM in response to K Shaffer

Hi and thanks for your answer.

This morning I opened my iMac and it was pretty dirty, I mean it was dust everywhere, I cleaned it up and closed it. It started fine, a little bit slow, and when I was about tu use CleanMyMac (i had about 29 gb of trash that detected the programa last night when it crashed) and the same thing happened, the "snow pixel" and didn't want to start and freezes.

I'm doing right now the AHT (the extensive version) again but it takes too long (about 30 mins o more I think) and it cant finish. I dont know what can be.

I got my iMac in early (january) 2011

Model: iMac 11,2

CPU: Intel corte i3

Originally came with snow leopard and about less than a year I uploaded to Mavericks (I should mention that when I was uploading I had some troubles, my OS crashed in the middle of the installation and needed to install de original OS from the DVD aaaand then downloaded de mavericks again and installed it, since then I never had any other trouble but this)

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Answer 3

rkaufmann87

Level 10

140,856 points

May 2, 2015 1:11 PM in response to bnl18

CleanMyMac is considered malware, DO NOT install it and if you already have uninstall it immediately. Macs do not require cleaning, antivirus or any other third party utilities to maintain themselves.

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Answer 4

SeaPapp

Level 7

26,486 points

May 3, 2015 11:57 AM in response to bnl18

Uninstall Clean My Mac http://macpaw.com/support/cleanmymac2/knowledgebase/how-to-uninstall-cleanmymac- 2

The AHT error you reported relates directly to the hard disk cooling fan which is controlled by the hard disk itself. 99% of the time I've seen that error the hard disk was failing. Hopefully you have a backup and you need to make an appointment and take your iMac in for service. If you choose to replace the hard disk yourself you can find step by step instructions at iFixIt.com

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Answer 5

bnl18 Author

Level 1

8 points

May 2, 2015 3:43 PM in response to SeaPapp

Woah, I didn't knew that, but thanks! i'm uninstalling the app right after my backup is ready (I mean i just wanted to save some photos and docs, anything else can go away)

If this is related to the cooling fan controled by the hard disk... Replacing the hard disk might be the solution? Because I had an "extra" 1tb hard disk (my mac has a 500gb hard disk) that I can use.

Or what other solution do you have? I can't take my iMac to an iShop por something because the closest one is pretty far away from my home.

So please tell me what el se can I do and why happened this to my HDD.

Thanks a lot!!

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Answer 6

SeaPapp

Level 7

26,486 points

May 2, 2015 3:59 PM in response to bnl18

If it were mine, and especially if I had an extra disk laying around, I would replace the hard drive. I believe that the drive needs to be the same manufacturer as the original or the thermal sensor in the drive won't match and your fans will run wild. Do some research, OWC is a good resource for advice.

Why it happened is easy......there are two kinds of hard drives.......those that have failed and those that will fail. It's as simple as that.

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Answer 7

bnl18 Author

Level 1

8 points

May 2, 2015 4:12 PM in response to SeaPapp

I dont really know if my extra hard disk is from the same manufacturer, in case they're different i suppose it is better not to do anything? Or maybe try to replace the fan?

I read that maybe the OS can be causing some kind oc "error" on the values related to the fan and stuff, if I reinstall the original OS that came with my iMac (snow leopard) you think maybe can make some difference?

Sorry if i'm bothering you with so many questions but I've never had any problems with any other apple device and this is freakin me out:(

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Answer 8

SeaPapp

Level 7

26,486 points

May 2, 2015 6:13 PM in response to bnl18

You can try reinstalling the OS, it won't hurt, but I'll be surprised if it actually helps. While The Apple Hardware Test can be unreliable when it doesn't report an error it's pretty much spot on when it does.

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Answer 9

bnl18 Author

Level 1

8 points

May 2, 2015 9:48 PM in response to SeaPapp

Yeah you we're right, I deleted everything in my hdd and reinstalled the OS from the original dvd (snow leopard) and went pretty fast, I was excited because of this and then tried to do an AHT again (the one that I tried this afternoon never finished because it was freezed my mac at the end of the proccess) and freezed out, then the "snow píxel" came and I knew that it was useless to do something else.

I think i should use my other hdd and trhow away this one, at least I had some backup 😟

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Answer 10

SeaPapp

Level 7

26,486 points

May 3, 2015 11:57 AM in response to bnl18

Try putting the other hard drive in an external case and using it that way. It'll be slower but it's one way to eliminate other hardware concerns and zero in on the internal hard drive.

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Answer 11

bnl18 Author

Level 1

8 points

May 3, 2015 11:56 AM in response to SeaPapp

Hi there, I was about to do what u said, then i remembered that I don't have here my extra 1tb hdd.

Then I tried my iMac hdd on another computer with windows 8 as an external hdd. It was difficult to the pc to read, I deleted everything and leave the hdd empty, make run the windows problem solver on my hdd and reported some motor problem, so this support the errors from the AHT, right?

When my hdd was tested in that win8 pc, the pc was pretty slow and it was obvious that something was wrong.

So this next weekend I'm going to change my old hdd for the 1tb hdd, so wish me luck and I'll be posting how was it.

And hey, thanks a lot for your time and opinions, have a nice day!

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Answer 12

SeaPapp

Level 7

26,486 points

May 3, 2015 1:48 PM in response to bnl18

You're on the right track. Good luck. Do be sure to post back and let us know how it goes.

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Answer 13

bnl18 Author

Level 1

8 points

May 9, 2015 9:12 AM in response to SeaPapp

Hi again!

This morning I've changed de hdd, I struggle a little with some cable (the one that conects the vídeo with the display) I put everything in place, started everything and when the screen was on... The same problem. Some annoying píxels appear. I just open the mac again and my dad said (he is some electronic engineer) that it was some.vídeo problem and maybe the cable (the one that gave us problems) was a little bit loose, de tried and tried, dad make some things to make it easier because of the pins and blabla but the cable never was estable, always was poppin out and stuff, so in one of many tries the cable was broken and obviously I'm going to buy another one.

But what scares me a lot is that the same snow pixel it's there again so I don't know if the cable could be the reason of al this crazieness and if someone knows what can be 😟

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Answer 14

SeaPapp

Level 7

26,486 points

May 9, 2015 11:23 AM in response to bnl18

I wish I could tell you exactly what the problem is, but obviously it's impossible to diagnose a hardware problem without access and the proper testing tools. The only thing I know for sure is that the original AHT code relates to the hard drive fan motor which is controlled by the HDD.

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