Introduction

If you ever find that the sensors on your ESXi server show an Unknown status. You may think a reboot is your only option to get it functioning again however not true.

Solution

If you SSH to the system and restart the service using:

~ # localcli hardware ipmi sel clear
~ # /etc/init.d/sfcbd-watchdog restart

Then click the reset sensors button. Everything will start working again. https://serverfault.com/questions/549443/vmwre-esxi-5-hardware-health-status-shows-unknown