Bug ID 437637: Sensor critical alarm: Main board +0.9V_CN35XX

Last Modified: Oct 07, 2023

Affected Product(s):
BIG-IP AOM(all modules)

Known Affected Versions:
11.4.0, 11.4.1, 11.5.0, 11.5.1, 11.5.2, 12.1.0 HF1, 12.1.0 HF2, 12.1.1 HF1, 12.1.1 HF2, 12.1.2 HF1, 12.1.2 HF2

Fixed In:
12.0.0, 11.6.0, 11.5.3

Opened: Nov 12, 2013

Severity: 4-Minor


TMOS may log a critical alarm for the 0.9 volt sensor even though the voltage is in the nominal range. Bug 447349 is a duplicate of this bug. The log message reads "Blade 0 hardware sensor critical alarm: Main board +0.9V_CN35XX voltage: 888 mV"


There will be a single ltm log message indicating this critical alarm, however the voltage reported in the log message will be in the nominal range.


When the host is powered off using the AOM menu, the LBH will detect an under voltage condition for all non-standby voltage rails. This puts the sensors in the critical state. When the host powers the voltage rails turn on and the sensors transition back to the nominal state as the voltage rises. The 0.9 volt rail on some systems does not get high enough to clear the alert even though the voltage makes it into the nominal range.


Do not power cycle the host with the AOM menu. This error does not occur with an AC power cycle.

Fix Information

The 7000 Series platform no longer reports a false positive sensor out-of-range error when the Host is powered off using the AOM.

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips