Voltage Battery (VBAT) Lower Critical Sensor Threshold Asserted Error


Maintenance & Performance



Voltage Battery (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 a message such as VBAT: Lower Critical sensor threshold asserted or SN:BB +3.3V Vbat ST:Voltage ED:Lower Non-critical - going low ET:Asserted is seen, proceed as follows:

  1. Clear the CMOSRefer 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. If this does not resolve the issue, follow How to Replace the Complementary Metal-Oxide-Semiconductor (CMOS) or System Battery on Intel® Server Board Family? to replace the 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.