Water Spill = Kernel_Task 320%, Fan loud, Slow MBA. Why?

Discussion in 'MacBook Air' started by xulotran, Apr 11, 2015.

  1. xulotran macrumors newbie

    Apr 11, 2015
    Hi all,

    After days of research and homework, I finally decided that asking my own question might be the way to get the best answer to my problem.

    I own a Mid 2012 MacBook Air 13" i7, 8gb memory and 256 SSD.

    Back in 2013 I went for an offroad trip, the car sank in the river, the Air was inside the Car. Wet.

    Back home I opened the Air, cleaned as much as I could with isopropyl, let it dry few days and tried to boot. It didn't.

    I replaced the battery and I could finally plug it to A/C and press ON. But then the fan would progressively reach its max speed and when I was at the step of entering my password it would die. Everytime.

    What did I do? I bought a second-hand Pro. Been using it for the last two years and no problem. So three days ago I decided to sell the water spilled Air online to make a few bucks.

    But my curiosity was too strong, so I plugged it to A/C and press ON. It booted and this time it did not die!

    So I did some research. I went into Activity Monitor and saw: Kernel_Task 320% and CPU system usage at 98% leaving barely 2% for the user.

    Then I checked IStat Pro, the fan speed is at 6500rpm but the CPU temperature is barely over 32C/90F and the bottom case doesn't feel warm at all when touching it.

    Memory usage seems fine.

    I tried to boot in Safe Mode but it was even slower. 20min to open Activity Monitor so I went back to normal mode.

    I launched AHT and it gave me:

    4SNS/1/C0000008: Th1H - - 124

    I understood that T means Temperature and h means Heatsink.

    But will replacing the heatsink and thermal paste really fix my Air? Is there temperature sensor within the heatsink that gives false information to the CPU forcing it to run the fan at max speed and be so aggressive with the kernel_task?

    I'm quite happy to be able to boot it today even after two years stored in its box waiting for me to advertise it online. So if I could fix it I would be very happy and I would definitely keep it and get rid of the Pro that I bought as a (long term) replacement.

    Any thought and advice on what is the problem or what should be my next step would be very appreciated.

  2. Airboy1466 macrumors 6502


    Feb 23, 2015
    The fans do that as s defensive mechanism implemented by apple that's also an indication that there is something wrong with the computer what you should do is put the computer through an apple hardware test the command to do it is " power off computer plug in power adapter press power button then immediately hold down D key until you see spinning globe" it will tell you what needs to be replaced you can also try resetting the "pram" that may also stop the fans from spinning
  3. xulotran thread starter macrumors newbie

    Apr 11, 2015
    Thanks Airboy1466,

    Last night I restored OSX, and this morning I reseted PRAM and SMC.

    I just went into Activity Monitor and I don't see Kernel_Task on the screen anymore. That's a good news though I don't know which reset made it disappear.
    BUT, the fan is still loud, the computer is still slow and the CPU system usage is still at 82%, Idle 15% and User roughly 3%.

    I did an Apple hardware test yesterday which gave me 4SNS/1/C0000008: Th1H - - 124 as the only error code.
    On Cnet I found a page explaining the code, and in my case it means that there is an issue with the Heatsink temperature sensor.
    Here is the link: http://www.cnet.com/news/how-to-invoke-and-interpret-the-apple-hardware-tests/

    My main question is: Is the heatsink an electronic component with a sensor? If so I will definitely replace it. If not then what else can create this error code?

    Thanks for your help.
  4. xulotran thread starter macrumors newbie

    Apr 11, 2015

    Kernel_Task are still there at 342% CPU usage. The reason why I couldn't see it in Activity Monitor this morning was because I did not click "All Processes".

    I found an interesting method found on several forums which worked for several people suffering from high Kernel_Task usage.
    1. Go to About this mac under the apple in the upper left and click on More info
    2. Click on system report
    3. make a note of what it says after Model Identifier
    4. go to your master drive – System -Library – Extensions – IOPlatformPluginFamily.kext -Contents – Plugins –ACPI_SMC_PlatformPlugin.kext – Contents – Resources – find the name from step 3 and move it to a folder that you can find again if needed.
    3. Restart and you’re done

    Here is the link:

    It might help others but it did not fix my problem. Still investigating. Any thought is appreciated. Thanks
  5. Airboy1466 macrumors 6502


    Feb 23, 2015
    Ok so how is everything do you still need trouble shooting advice
  6. Lucas Godfrey macrumors 6502

    Lucas Godfrey

    Jul 12, 2010
    Somewhere between Here and There
    the heatsink does not have a temp season in or on it.
    this sensor is on the logic board near to the heatsink, try to disassemble the laptop completely and give the whole board a nice scrub with isopropyl using a soft brush like an old toothbrush.
  7. iMacC2D, Apr 16, 2015
    Last edited: Aug 12, 2017
  8. ibravo macrumors newbie

    Apr 20, 2015
    I did have the same problem with a 2012 MacbookAir 6,2 : Water spill

    After doing a hardware test, it came back with an error message that I was not able to decrypt, but I did resemble the issue that one of the sensors was giving a bad reading, thus OSX was throttling the CPU to decrease the (assumed) high CPU utilization.

    I made some progress that I want to let you guys now:

    1. The high CPU utilization is indeed an OSX defensive mechanism. In OSX everything runs slowly as a result of this issue.

    2. Installed a Mac Fan control. This reduced the noise of the fan, but still high CPU utilization. One odd thing was that this program was able to read the CPU temperature sensors and they did not seem to be out of control. So my broken sensor would most likely be other.

    3. Partitioned the SDD and installed Ubuntu. I've migrated from Ubuntu to Mac before, so the reverse was a no brainer. This is where things get interesting:

    Under Ubuntu, the CPU is roaming at around 35-40 C and the computer is as responsive as before. I am now battling with the fan as it is stuck in 100% (6500 rpm) and the noise is killing me at the office, but the computer is back to life and useful.
  9. motrek macrumors 68020

    Sep 14, 2012
    I wonder if the high CPU utilization is due to some sort of software CPU throttling to get temperatures under control. The kernel might just be sending a bunch of NOPs to the CPU to cool it off but if you look at Activity Monitor it looks like it's busy doing something.
  10. ibravo macrumors newbie

    Apr 20, 2015
    More information on the CPU throttling here:


    This article gave me the insight that the OSX kernel is the one managing the high CPU, and since my machine (Macbook air 6,2) was not in the list of options, the fix proposed in the article did not work for me.

    There was a follow up article in a different website that mentioned that since a later time, the location of these kexts was moved to a different path, and were referenced by a computer ID instead. The solution proposed was also to eliminate the file in question. That did not work in my case either, thus the intention to move to Ubuntu.
  11. tobiasvdp macrumors newbie

    Dec 30, 2008
    this is probably due to a defective i/o flex cable - please inspect the connectors on both sides, the connection to the logic board is especially interesting as the pins can get bent quite easily...

    if for instance a charger is connected and osx is not able to identify make and model, the cable is probably the reason...

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10 April 11, 2015