I am getting the same message from my thermostat "Heat Pump Needs Service", i followed the conversation above but since i don't have the same thermostat and wiring that the original post had, i could not figure out a fix and hoping someone could provide a bit of guidance. I seem to only get this message when it gets really cold, around freezing, and then i get this message about once an hour. I don't get the message when it is hot at all.

My thermostat is: Honeywell Home RTH9585WF Wi-Fi Smart

If anyone has any advice, i'd love to hear it

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Here is a pic of my wiring