poweredge 2650 voltage sensor failure

I have the openmanage server administrator program loaded on my poweredge 2650. It has redundant power supplies. 

I have noticed recently that I get red stop messages in the Windows event log viewer.  The actual messages tend to vary, but they occur about once a day in a group all at once. 

E.g. Voltage sensor failure ESM ROMB PK Volt, voltage sensor ESM GB1 1.8 Volt, ESM MB -12 Volt, ESM CPU volt.  Occasionally but not always I see Power System Unit, Power supply 1 redundancy lost.

The strange thing is, a little while later, I get messages to say everything is working normally again, redudancy restored etc.  I am not intricately familiar with the poweredge servers, can anyone point me in the right direction ?  It looks to me like the system is seeing failures of the voltage sensors themselves, then they start working again.  I have never had this system fail.  It is about 5 years old, and past the warranty period so I can not call Dell support.  I have updated firmware, ESM etc to latest patches. The server is running on a UPS that is shared with another server that doesn't have these errors,therefore in my mind it can't be the UPS.  The PS isn't failing because the power is being lost either.

I am wondering, if I replace the power supply 1, will this stop the messages, or are the voltage sensors separate from the power supply ? Anyone can decipher what these messages mean ?  I have googled them, and looked on Dell's support site but haven't found anything yet.

Thanks in advance.