Model A1312 / Mid 2011 / 2.7 & 3.1 GHz Core i5 or 3.4 GHz Core i7 Processor, ID iMac12,2

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Prohibitory sign 3 times at start, then it boot and works well


Few months back, (i think after El Capitán), when I power on my iMac, when the apple icon should appear, it shows a prohibitory sign and stays there a few seconds. Then the apple icon appears.

This occurs two more times, and when the apple icon appear the third time, it shows the normal loading bar and OS X boot as always. Then the computer works completely fine.

There is another problem, that I don't know if is related. Three months ago I checked the S.M.A.R.T. of my devices and I noticed that even with "PASSED" status, the HDD (secondary), fails in the Airflow Temperature Celsius field, showing around 60 degrees every time, even if I just turned on my computer. This HDD also have 37000 working hours, so I'm a bit scared.

Knowing this, yesterday I did an Apple Hardware Test. In the quick mode of this test it showed an error with the code "4MOT/4/4000003: HDD-1525". Looking in some forums I see references about HDD temperature (related to the 4MOT/4/4000003 part, HDD-1525 seems to be another thing I don't know).

So now, I don't know what I should do, cause I think the error on the airflow temperature field of the S.M.A.R.T. could be caused by a failing sensor, because it happens since a long time and even with the computer just turned on. I also don't know if the error showed on the Apple Hardware Test is related with the S.M.A.R.T. error (which is a thing a test could do).

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I just noticed about this comment (I only saw your full answer), but that's the page I found when searched about the prohibitory sign (also got the name from there).


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Sounds like your HD is having a hard time. Do you have a second system or a bootable drive you can boot your system up with?

Basically, we want to use an external system or drive to run Disk Utility from to test your internal drive.

The temp error is to be expected as the drive is over working trying to locate/access the blocks of the OS and/or the files requested.

At this point I would test the drive, If you have anything on it you don't want to loose this is the time to copy off the files as you will likely need to reformat the drive to get running again. Even still the drive is failing so you might want to look for a new drive. I recommend going with a SSHD or SSD it depends on how much space you require. The other option here is to add a second drive, here we put a standard HD in and a SSD.

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Hello Dan, thanks for the answer.

My iMac already have 2 disks, a SSD with the OS X system and this HDD, so that's why I doubt if the two problems are related.

As far as I saw in the Apple website the prohibitory sign it's about the system cannot locate the OS X boot properly. But my SSD is ok (i think...), the overheating problem is on the secondary HDD with has only files that I already backed up, but I still need to make a time machine backup of the SSD and copy it somewhere else.

Apart from that, after the prohibitory sign appears the third time, my system boots as normal, so if you want me to run some kind of test, I could do it from the same system.


You may have two drives (HD & SSD) but it appears the drive selected as the boot drive is the HD. Again you'll still need to get the system to boot up with a working OS to address things. Press the Option key so you gain access to the disk manager and try selecting the SSD to see if it will boot up. If not it does not have the needed files or it too is having issues.


Thanks for answering so quickly again.

I think you didn't understand me. My OS X system boot up perfectly after showing that sign three times. Is completely usable and I was using it (and I'm still) until now without any problem except that sign on the boot (which appears three times every time I turn on my computer or restart it).

I don't really know how the boot options of OS X works, but the secondary disk (the HDD) never had an OS X system installed on it. Also, from System Preferences > Startup Disk, I can only see my SSD.


Go into System Prefs and look at what Startup Disk reports as the startup drive. Select your SSD and reboot did that fix it? Basically, the HD is selected (even if it doesn't have a working OS) so it try booting from it then cascades over to the next found drive and then it finds it has a working OS to boot up from.


Hello Dan. Thank you again for the answer. I can't believe this, but it seems that in some moment (maybe when I upgraded to El Capitán) my system stopped defining the SSD as the default boot device.

When I went to see that preference before telling you about that the SSD was the only device there, I didn't noticed it, but if you have a default boot drive, there is a text below the device list saying it. In that moment, there wasn't any text in that window, now after selecting again the SSD as boot device, there is.

I reboot my system and guess what, no prohibitory sign anymore.

The question about the HDD overheating (and the S.M.A.R.T. error about it, that I don't know if could be caused by a bad sensor or something) is still around there, but you solved a great part of my problem, thank you.


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hey RixxzZ can u tell me how you manage to solve this problem? because i have the same problem after upgrade my macbook pro 2011 to ssd.

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He reset the boot disk setting to a working drive. His internal drive was failing.

How about posting your own question. I'm sure if you did you'd get a better answer than posting here. Besides this is an iMac not a MacBook Pro so things are a bit different.


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RixzZ will be eternally grateful.
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