[Problem] PC only accessible via Intel AMT - "Unknown Sensor Type #7"


I have a lenovo M92 tiny, that works fine for a few minutes, boots up into windows, but after maybe 2 or 3 minutes, I loose video and Keyboard access. The NUM LED dies and Kepresses have no result.
The fan keeps spinning and I get no beep codes.
I can access the pc via its Intel AMT interface but remote desktop and Serial over Lan can connect but remain empty. Also reboot commands fail.
I have to disconnect the pc for a while from power to get it working again.

Troubleshooting So far:
1. I made sure that the Powersupply is OK. I tested with a known good one and that seems not to be the cause here.
2. I updated the BIOS to the latest available. It updated just fine, right in time before I lost access to it. So luckily no brick here.
3. I completely disassembled the pc, applied new thermal paste and made sure the fan and stuff is clean. The CPU and PC Temps remain OK. Nothing too hot.
4. The PC has a I3 second gen CPU, but I also tested it with a known good I5 3rd gen. But the pc shows the same errors.

In the Event logs in Intel AMT, I can see errors : "Unknown Sensor Type #7"

m92 unknown sensor.PNG

I checked the System Event Log Manual from here: https://www.intel.com/content/dam/suppor…ootingGuide.pdf

The Log is actually a Intel AMT Notification Alert. But I cant find the exact code in the manual:


But couldn’t find that exact error code.
What is Sensor Type 7?

Anyone knows what the problem is here?

EDIT by Fernando: Tread title shortened (was too long) and unneeded blank lines removed (for better readability)