my kernel task is using 400% of my CPU

Carloshumberto,

if you boot into Safe mode, does your MacBook Pro still run very slowly?

The kernel is using excessive processor cycles. Below are some possible causes for the condition.

Throttling

When it gets high temperature readings from the hardware, or a low-voltage reading from the battery, the kernel may try to compensate by interrupting the processor(s) to slow them down and reduce power consumption. This condition can be due to

• a buildup of dust on the logic board
• high ambient temperature
• a worn-out or faulty battery in a portable
• the malfunction of a cooling fan, a temperature sensor, a voltage sensor, or some other internal component

Note that if the problem is caused by a sensor, there may be no actual overheating or undervoltage.

If the computer is portable, test with and without the AC adapter connected. If kernel_task hogs the processor only on battery power, the fault is in the battery or the logic board. If it happens only on AC power, charging is causing the machine to heat up. That may be normal on some models. CPU usage should drop when charging is complete.

Apple Diagnostics or the Apple Hardware Test, though not very reliable, is sometimes able to detect a fault. For more thorough hardware testing, make a "Genius" appointment at an Apple Store, or go to another authorized service provider.

If nothing is wrong with the hardware, then whatever you can do to improve cooling may help.

Installed software

User-installed software that includes a device driver or other kernel code may thrash the kernel. That category includes virtualization software, such as Parallels and VMware, as well as most commercial "anti-virus" products. Some system-monitoring applications, such as "iStat," can also contribute to the problem. You can test for this possibility by completely disabling or removing the software according to the developer's instructions, or starting in safe mode. Note, however, that disabling a system modification without removing it or testing in safe mode may not be as easy as you think.

Corrupt NVRAM or SMC data

Sometimes the problem is cleared up by resetting the NVRAM or the SMC.

External display

Connecting an external LCD display to some MacBook Pro models may cause this issue. If applicable, test by disconnecting the display. You might get better results with a newer LED display.

Carloshumberto,

I can’t add anything to the instructions on the Apple page which was linked in my previous reply. If you are holding down a Shift key at the proper time and releasing the Shift key at the proper time, then there is nothing that I can do to make your Mac start in Safe mode.

Have you tried any of Linc Davis’ suggested alternatives to Safe mode?

Carloshumberto,

if running in Safe mode did not make a diference, then the next thing to try would be to reset your MacBook Pro’s System Management Controller. Does that make a difference?

Carloshumberto,

have you tried running your MacBook Pro’s Apple Hardware Test, to see if it can detect any problems?

Carloshumberto,

I hope that you will be able to find a satisfactory hardware repair service.

Can I ask if you have more than 1 external display plugged in?

I ask because I've 2 and when I unplug the second, I get the kernal_task return to as low as 6%. When I have both external displays plugged in I hit up to 500% CPU time. I've logged a bug with Apple as my friend also has the same issue (he's using 1 TB-DVI and 1 HMDI whereas I'm using two TB-DVI)