Macbook Pro 13" 2011 kernel_task high cpu load

Discussion in 'MacBook Pro' started by Arctix, Oct 15, 2011.

  1. Arctix macrumors newbie

    Oct 15, 2011

    I have a 13" 2011 Macbook Pro since it was released and have got no problems with it until last month. My Macbook occasionally lags or becomes very slow at random moments. When I check activity monitor, it shows that the process: kernel_task has 250-300% CPU load. What's very odd about that is that my CPU doesn't get hot at all (and fans don't spin faster). I initially thought the problem was with Lion, so I patiently waited for 10.7.2, but since the problem still persists, I did a clean install yesterday. Today, I used my Macbook again and the problem is still there! I did multiple hardware tests and most of the times, there are no problems found, however, last time it showed the error: 4SNS/1/40000000: IC0R-12.793. I googled a bit but didn't find very much, I think there's something wrong with a sensor.

    Can anyone help me out here? :)
  2. Arctix, Oct 15, 2011
    Last edited: Oct 15, 2011

    Arctix thread starter macrumors newbie

    Oct 15, 2011
    I forgot to add that this issue probably started after I did the Lion EFI 2.2 update for Macbook Pro last month, don't really know if this has anything to do with it. I also just did 3 more hardware tests, 1 extended and two short tests. No hardware errors found. I'm kinda confused right now :S. Is the hardware test always right or can it be wrong?

    Hope someone helps me out :(

    EDIT: Did some further research by downloading Temperature Monitor app. I looked if there was any sensor malfunctioning and the only odd thing I came across was that CPU Core 2 and 4 don't always display their temperatures (it's always those 2 cores). Sometimes the only temp I don't see is core 2, sometimes core 4 and sometimes I can't see both. Right now, I can see all the temps. It's like the sensors are sometimes having troubles displaying it. Is this normal behavior? Do the cores shut down or is there a problem with my sensors? It's a i5 base 13 inch MBP btw.

  3. mikkyfikky macrumors newbie

    Oct 17, 2011
    Does overheat so that it autoshuts down?

    I have the exact same macbook. The heatsink B sensor would reach temperatures of 126C and shutdown. I took it into the apple store and they replaced the heat sink but the problem still happened after they fixed it!

    But over the weekend, when I repaired the disk and disk permissions (we owe that to Mac Os' Unix heritage), it runs cooler and hasn't gotten so hot that it shutsdown. Also, kernel_task hasn't spun out of control which slowed my machine down so that it was barely usable.

    So try rebooting into the recovery partition(hold the alt option key down when pressing power button). Go into disk utility and fix the disk and repair the disk permissions. I actually ran it a couple of times so might want to do that too.

    Here is my theory.. with broken permissions, there must be a bug in spotlight and it goes crazy trying to access the disk. Perhaps the built in I/O controller chipset is working overtime (the high load generated by kernel_task with low CPU temp and high heatsink temp seems to point to that). Also, when kernel_task starts working overtime, can you look at what your disk activity is at in the activity monitor? Since I don't have the problem anymore, I'd like to validate my theory. Let me know how it goes... it seems alot of people have this problem after upgrading to Lion.
  4. GuitarG20 macrumors 65816


    Jun 3, 2011
    this, but you can do it with "disk utility" within OSX... you don't need to load the recovery partition...
  5. mikkyfikky macrumors newbie

    Oct 17, 2011
    you can but sometimes the files are locked when when you are using the OS. Using the disk utility in the recovery partition can be more thorough.

Share This Page