Do late-2015 27" 5K iMacs have an AC/DC T2 secondary heatsink thermal sensor?

Since yesterday, on my iMac (A1419 EMC 2806) the fan is maxing out from power up, regardless of safe mode, recovery mode, or booting into Windows (via Boot Camp), diagnostics return PFM006 (SMC error) Assuming a thermal sensor defect, I installed iStats to check the thermal sensors. Readout below in the screenshot - all temperatures are within normal ranges, the fan is at maximum and also won't slow down if I try to do that manually, and the only temperature that's missing is the one from the power supply unit (AC/DC T2 secondary heat sink). So my question is: Is there even such a sensor in that model, do I expect a readout here? Have I thus found the probable cause and should be looking into the connection or the sensor itself? (No other hardware or software changes made recently)