CPU fan error is a common boot-time warning that can stop your PC from working properly. In this guide, we cover everything about the CPU Fan Error and how to fix it for good. If you have been stuck with other Windows boot issues, many of the same troubleshooting principles apply here as well.
What Is CPU Fan Error?
CPU fan error is a warning message that may appear when your Windows PC boots up. It usually shows up after the computer has shut itself down due to overheating, which happens when the fans cannot cool the hardware properly. If you see this warning, you should address it quickly because prolonged overheating can permanently damage your components. Keeping your PC hardware in good shape starts with proper cooling.
What Causes CPU Fan Error?
A CPU fan error can be caused by physical damage to the fan, incorrect BIOS settings, or factors that cause the computer to overheat and force the fan to run at abnormal speeds. Dust and debris blocking the air vents or fan blades can also trigger the error. Older motherboards are especially sensitive to fan detection and may throw this error even when the fan is working fine.
What Happens When This Message Appears?
Unexpected Shutdown
The system is designed to force a shutdown if a CPU fan is not detected. This safety measure protects the processor from heat damage. You may experience sudden shutdowns shortly after powering on.
Burning Smell
An overheated CPU running above 300 degrees Fahrenheit can release a smoky burning odor. This is a clear sign that your cooler is not working. If you smell burning, shut down the PC immediately and inspect the cooling system.
Motherboard Damage
While newer motherboards have better thermal protection, older models can suffer permanent damage from sustained CPU heat. Replacing a damaged motherboard is expensive, so early intervention is key.
How to Fix the CPU Fan Error
1. Clean the Air Vents. Dusty air vents are one of the most common causes of cooling problems. Use a vacuum cleaner or compressed air to remove dust from the vents and fan blades. Regular cleaning prevents heat buildup and keeps your system running smoothly.
2. Stop Overclocking. A CPU running at higher speeds generates more heat. The stock cooler that came with your processor may not be sufficient for an overclocked chip. Return to default clock speeds to see if the error goes away.
3. Inspect the CPU Fan Physically. Check if the fan has any broken blades or obstructions that stop it from spinning properly. On a desktop PC, open the case and look for visible damage. For laptops, professional inspection is recommended as opening the case may void the warranty.
4. Try an Alternate CPU Fan Header. Plugging the CPU cooler into a different fan header on the motherboard can sometimes resolve detection issues. Consult your motherboard manual to find the correct CPU_FAN header.
5. Check CPU Fan Settings in BIOS. Restart your PC and press F1, F2, or Del (depending on your motherboard) during boot to enter BIOS. Navigate to Advanced Settings > Hardware Monitor > CPU Fan. Enable “Active Heat Sink” and “Fan Duct with Fan.” Disable “Passive Heat Sink” and “Fan Duct without Fan.” Save changes and exit.
6. Bypass the Fan Error in BIOS. If you have confirmed that your CPU temperatures are normal but still get the error, you can bypass the warning. Enter BIOS and go to Monitor > Fan Speed Monitor > select your CPU fan > set to “Ignore” or “N/A.” Save and exit.
7. Replace the CPU Fan. Fans have a limited lifespan. If your fan is old, making unusual noises, or not spinning at all, replacement is the most reliable solution. Consider upgrading to a quality air cooler for better long-term performance.
8. Ensure Proper Airflow. Good case airflow is essential for keeping all components cool. Make sure you have intake fans at the front and exhaust fans at the rear. Cable management also helps by reducing obstructions inside the case.
Additional Tips
Apply fresh thermal paste between the CPU and cooler if you are comfortable doing so. Old thermal paste loses its effectiveness over time. Also check your power supply unit (PSU) – a low-wattage PSU may not provide enough power for the fan to run at full speed. If you are dealing with other Windows hardware issues, similar diagnostic steps can help.
Conclusion
These eight methods cover the most common ways to resolve a CPU fan error. Start with the simple fixes like cleaning and checking connections, then move on to BIOS tweaks if needed. If the problem persists after trying all steps, take your PC to a professional technician for a thorough inspection.
Frequently Asked Questions
Why does my computer say CPU fan error?
The message appears when the system detects that the CPU fan is not working properly or is not detected at all during boot.
What happens if the CPU fan fails?
A failed CPU fan causes the processor to overheat. Modern motherboards force an automatic shutdown to prevent permanent damage to the CPU and other components.
How do I fix a Lenovo CPU fan failure (Error 0135)?
Reset the BIOS by turning on your PC and pressing F1 until the Lenovo logo appears. Press F9 and select YES to reset. Press F10 to save changes and restart.
What is a healthy CPU temperature?
A desktop CPU typically runs around 120 degrees Fahrenheit (49 degrees Celsius) when idle and up to 175 degrees Fahrenheit (80 degrees Celsius) under load. Anything above 190 degrees Fahrenheit (88 degrees Celsius) may indicate a cooling problem.
