I have the same problem with 4 120c PN fw 4.7 and i couldn't solve it yet.

Starter help sais:

'F01611 SI CU: Defect in a monitoring channel v4.4, 1951: Module temperature not plausible.' but no remedy sugestion is present.

The bigest issue is that a simple Acknowledge does not make the fault go away, and i have to reactivate the safety functions, which means that someone with Starter has to be in the plant all the time.

If anyone knows atleast a simplier solution to Ack the fault please tell us.

Thank You.

This is what Siemens replied to me for the same issue:

"We are still investigation the issue with F1611 1951.
At the moment it looks like a combination of EMC and software timing, we have not had reports of faults with FW4.6 so if you required an interim fix till a new 4.7 firmware is release, you can downgrade the units. The parameters should not be affected but you will have to do a safety acceptance test. If you have failures with FW4.6 please report them.
You can download Fw4.6 from the link below
http://support.automation.siemens.com/WW/view/en/67385235
A new version will be release in the next few weeks for FW4.7"