How to Fix and Troubleshoot Kernel_task High CPU Usage on a Mac

Kernel_task is an essential background process in macOS that helps manage your Mac’s CPU temperature and workload. However, sometimes kernel_task can use an unusually high percentage of CPU, slowing down your Mac. This article will provide a comprehensive guide on troubleshooting and fixing kernel_task high CPU usage on a Mac.

What is Kernel_task?

Kernel_task is part of the macOS kernel, the core of the operating system. Its main functions include:

  • Regulating CPU temperature by throttling system resources for CPU-intensive applications
  • Prioritizing system tasks and workload
  • Ensuring smooth operation between hardware and software

Essentially, kernel_task acts as a “traffic cop” to optimize performance. It’s one of the first processes to start when you boot your Mac.

What Causes High Kernel_task CPU Usage?

There are several potential triggers for kernel_task using excessive CPU:


If your Mac overheats from intensive tasks, faulty fans, blocked vents, etc., kernel_task will throttle CPU performance to reduce temperature. This causes high kernel_task CPU usage.

Outdated Software

Using outdated OS versions or software with bugs can lead to kernel panics and high kernel_task CPU usage as it struggles to maintain system stability.

Faulty Hardware

Issues with components like the RAM, hard drive, or fans can result in overheating and high kernel_task CPU as it tries to compensate.

Resource-Intensive Apps

Some demanding apps that use a lot of CPU resources can also trigger kernel_task to step in and regulate workload.

Background Tasks

Auto-updates, Spotlight indexing, Time Machine backups, etc. running in the background can sometimes be quite CPU-intensive and lead to high kernel_task activity.

How to Check Kernel_task CPU Usage

To check kernel_task’s CPU usage:

  1. Open Activity Monitor (located in Applications > Utilities)
  2. Click the CPU tab
  3. Look for kernel_task in the list and view its % CPU

Activity Monitor CPU Usage

If kernel_task is using over 100% CPU consistently, you likely have an issue that needs troubleshooting.

How to Fix High Kernel_task CPU Usage

Here are the top recommended solutions for resolving high kernel_task CPU usage on a Mac:

1. Restart Your Mac

Restarting will refresh the operating system and quit all running processes. After rebooting, check if kernel_task CPU usage has reduced in Activity Monitor.

2. Update Your Software

Make sure macOS and all your apps are updated to the latest versions. Outdated software can trigger kernel panics and high kernel_task usage.

3. Reset SMC

The System Management Controller (SMC) controls your Mac’s fans and hardware. Resetting it can help if overheating is causing the kernel_task spike.

To reset SMC:

  1. Shut down your Mac
  2. For notebooks: Press Shift + Control + Option keys and the power button at the same time. Hold for 10 seconds.
  3. For desktops: Unplug power cable, hold power button for 10 secs, plug power back in.

4. Boot in Safe Mode

Booting in Safe Mode loads only essential macOS files and apps. If kernel_task CPU usage is still high in Safe Mode, it likely indicates a hardware or software issue.

5. Run Apple Diagnostics

Apple Diagnostics (hold D while booting) checks your Mac’s hardware and can detect failures causing high kernel_task activity.

6. Check for Malware

While rare on Macs, malware could be hijacking system resources leading to high kernel_task CPU usage as it tries to maintain stability. Scan with antivirus software to check.

When to Seek Professional Help

If you’ve tried all the above steps and kernel_task CPU usage remains consistently high, it’s best to take your Mac to Apple or an authorized service provider for hardware diagnostics and advanced troubleshooting.

An expert can run diagnostics to pinpoint any underlying hardware faults or software corruption causing the issue. They can also monitor system logs and traces in-depth to investigate why kernel_task behaves abnormally.

Seeking professional assistance is recommended if kernel_task high CPU usage persists despite your best efforts. Leaving the problem unaddressed risks permanent hardware failure or data loss from system instability.


I hope this guide gives you a good understanding of what kernel_task is, why it can use high CPU, and actionable troubleshooting steps to resolve the issue.

The key things to remember are verifying kernel_task’s activity in Activity Monitor, trying resets and Safe Mode boots, keeping your software updated, scanning for malware, and seeking professional help if problems continue despite your best DIY efforts.

Catching and fixing kernel_task high CPU usage quickly is important for maintaining the long-term health and stability of your Mac. With the right approach, you can get your system’s performance back on track.