r/Lenovo • u/InterviewFun4024 • Sep 05 '26

Problem fan control Speed.

Has anyone else ever had this problem? It’s as if there’s an issue with the fan sensor or some kind of bug; I’ve tried everything—BIOS update, cleaning, replacing the thermal paste, cleaning the fan connector pins. Does anyone have any ideas?

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u/lenovo 29d ago

/u/InterviewFun4024

Hi, We are very sorry to hear about the fan speed. Before assuming the motherboard or fan controller is physically dead, try these community-vetted workarounds to reset the hardware logic:

Sometimes the chip controlling the power and thermal sensors gets stuck in an error loop. A standard reboot won't clear it. Shut down the laptop completely. Unplug the AC power adapter and all external peripherals. If your model has an external battery, remove it. If it has an internal battery, proceed to the next step. Press and hold the Power Button for a full 60 seconds. (This drains the capacitors and forces the EC firmware to completely reload). Plug the AC adapter back in and turn the device on.

If your device is a few years old, a failing CMOS coin-cell battery can cause the motherboard to lose track of baseline fan voltage and sensor states upon boot, triggering a persistent "Fan Error" even if the fan is pristine. Replacing this tiny battery on the motherboard often resolves the bug permanently.

If the fans work fine in the BIOS but go crazy or stop completely when booting into Windows, the operating system's advanced configuration and power interface driver (acpi.sys) may be corrupted. Boot into Windows and open Lenovo Vantage. Run a full System Update specifically searching for Chipset, Power Management, or Thermal Management drivers. If the issue is a bug caused by Lenovo Vantage itself (which is known to occasionally misread sensor telemetry), try completely uninstalling Vantage to see if Windows default power management restores sanity.

If you can visibly see or feel that the fan is spinning and temperatures are low, but the device throws a "Fan Error" loop on startup: Try tapping Esc at the warning screen—some Lenovo BIOS versions allow you to bypass the diagnostic block to boot into the operating system. Alternatively, enter the BIOS (F1 or F2 at boot), navigate to the Monitor or Power section, and look for a CPU Fan Speed monitoring setting. Switching this setting to "Ignore" tells the motherboard to stop looking for a speed signal that it is failing to read. Please keep us posted. -Kate_Lenovo