Voltage Battery (VBAT) Lower Critical Sensor Threshold Asserted Error


Maintenance & Performance



VBAT is supplied by the CMOS battery when AC power is off (Battery voltage is 3.0 V) and by the main board when AC power is on (Battery voltage is 3.3 V).

If the “VBAT: Lower Critical sensor threshold asserted” message is seen, proceed as follows:

  1. Clear the CMOS. Refer to the board technical document for information about doing this. Alternatively, refer to the How do I clear CMOS? section on the How to Clear CMOS to Reset BIOS Settings in Systems with Intel® Desktop Boxed Processors page.
  2. Reseat the CMOS battery.
  3. Install a replacement CMOS battery.

More information

The VBAT sensor monitors voltage from the CMOS battery, a coin-sized battery on the baseboard. An error is logged in the Event Log if the voltage drops below the threshold in the Sensor Data Record (SDR) file. Refer to Table 13 of the System Event Log Troubleshooting Guide for the latest board models for more information.