621      iPhone_iPad_Mac_apple

Erreur 4sns/1/400000000:th00

Hello,

I've got this message after log hardware est because my iMac start but stop on a grey window with   in the middle.

what does it mean please?

thank you

Apple does not publish these codes and to be honest I have never seen this one before. We do know what some codes mean however this one is rare. I would recommend taking the computer to your local Apple Store or third party Apple Authorized Service Provider. If you don't know of any in your area please click the link below to begin looking for one.

An AASP can tell you what the code means and then provide an estimate of what it will take to repair the problem.

Good luck!

Apple - Find Locations - Country Selector

I've compiled a partial list of error codes over the years and the sns appears to be the System Sensor. As has been suggested, take your Mac to your nearest Genius Bar or AASP for a definitive diagnosis.

最后更新：2017-09-19 23:49:50

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