Error: Host hardware temperature status alert

Products

• VMware vSAN

Issue/Introduction

• In the "vCenter UI > Host > Monitor > Issues and Alarms", Hardware sensor alarms are reported on the ESXi hosts with error: "Host hardware temperature status".
• In the ESXi host , /var/run/log/hostd.log will show temperature hardware sensor status as "Red"

2026-06-25T03:10:14.9552 In (166) Hostd [2101746] : [Originator@6876 sub=Vimsvc.ha-eventmgr] Event 2388128 : Hardware Sensor Status: Processor Green, Memory Green, Fan Green, Voltage Gree, Temperature Red, Battery Green, Storage Green, Other Green

• In the host UI , There are hardware sensor alarms with "Assert and Deassert +Temperature" getting toggled. Similar events are also seen in vCenter UI.

• Alert persists in vCenter UI even though they are acknowledged.

• Hardware management console (iRMC) shows temperature within safe operating limits but in vCenter UI we may still see the temperature warnings.

•  In the vCenter UI , ESXi host's hardware health will report sensor warnings.

Environment

• VMware ESXi 8.x
• vCenter Server 8.x

Cause

The alert is triggered when physical hardware sensors (monitored by the BMC) cross thermal thresholds ie 36°C for Warning and 39°C for Critical. Even if the temperature returns to a safe level (Deasserted), the ESXi software layer (CIM/IPMI providers) may fail to synchronize, leaving a stale "Asserted" state in the vCenter cache.

 

• Below are the temperature threshold limits in Hardware management console (iRMC).

 

• Temperature hardware sensor alarms in the  "Hardware management console (iRMC)"  and vCenter UI will get triggered as below when the Temperature levels are crossed warning or critical threshold limits.

Resolution

Follow the below steps to clear the stale warnings on the vCenter UI

1. Identify the specific sensor triggering the alert by running the following command on the host: "localcli hardware ipmi sel list -p -i -n all".
2. Review the output for "Ambient" or "Inlet" sensor breaches.
3. Place the affected ESXi host in Maintenance Mode.
4. Reboot the host. This re-initializes the IPMI and CIM service providers and clears cached sensor data.
5. Verify "Hardware Health" status in vCenter UI.

Monitor the hardware management iRMC console and vCenter UI for recurring "Assert" events. If the alerts persist, engage the hardware vendor to investigate physical cooling or the faulty sensors.