Thermocouopler Problems?

Hello,

this is a more generic question. I use a M200 with Z-Temp. Recently I observed that during printing the color of the Z-Temp switched. The Z-Suite Temperature was given at 220°C, what means a green color of the Z-Temp. After 20-30 minutes of printing the color turned to red /purple, what means more than 260°C. After a few minutes the color turned back to green - what is ok.

So it was random that I could observe this, but it could be an explanation for some errors I had in the last time.

My question is: Can it be that the thermocoupler or the thermo sensor over the time cause failures and need to be replaced?