BIOS / UEFI Error Code
Systems & Devices
BIOS / UEFI
CMOS BATTERY FAILURE | RTC/CMOS battery issue
Industry
Systems & Devices
Canonical
/systems/bios-uefi/error-codes/cmos-battery-failure/
Last Updated
Feb 27, 2026
Summary
Firmware reported that the battery maintaining time/settings is not functioning correctly.
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What This Code Means
“CMOS BATTERY FAILURE” indicates the firmware detected an issue with the battery used to maintain time and configuration settings. It can lead to time resets and configuration loss, affecting boot and security validation.
Where Users Usually See This Code
- During POST at startup
- Firmware security checks (TPM/Secure Boot)
- Boot device selection and initialization
- Hardware monitoring screens
Why This Code Appears
- A required component did not initialize correctly
- Boot configuration could not find a valid device
- Security policy blocked boot
- Firmware detected a health or configuration issue
What Typically Happens Next
- Boot may stop or loop at startup
- A firmware message is displayed
- The system may enter recovery or setup screens
What This Code Is Not
- It is not safe to guess at hardware fixes
- It is not always solved by a firmware update
Troubleshooting Checklist
- □ Record the exact message and the device model
- □ Check official documentation for the specific OEM mapping
- □ Confirm boot order and whether the expected drive is detected
- □ Verify date/time settings if security validation is failing
- □ Avoid hardware disassembly unless qualified and instructed
- □ Use vendor support pathways for repeat boot failures
Notes And Edge Cases
Firmware messages and beep codes vary significantly by vendor and model.
Related Codes
8 links
- CMOS CHECKSUM BAD CodeFirmware settings invalid
- KEYBOARD ERROR OR NO KEYBOARD PRESENT CodeInput device not detected
- BOOT FAILURE CodeInsert system disk
- BOOT DEVICE NOT FOUND CodeBoot device unavailable
- CPU FAN ERROR CodeCooling issue detected
- OPERATING SYSTEM NOT FOUND CodeNo OS detected
- NO BOOTABLE DEVICE CodeBoot device missing
- PRESS ANY KEY TO BOOT CodeBooting from external media
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