DIAGNOSIS The Nest detected an issue with the 'Power Sharing' feature used with certain heat pump systems. It's protecting the system from a short cycle.
FIX This is usually a wiring or configuration error. In the Nest app, go to Settings > Equipment. Check if your system is configured correctly as a heat pump. If you have auxiliary heat (like electric strips), ensure the 'O/B' connector setting (for the reversing valve) is correct for your brand—O for most, B for some.
IF THAT DIDN'T WORK The error can trigger if the Nest's internal temperature sensor thinks the air coming from the system is too hot, indicating a stuck reversing valve or failed aux heat control. You may need an HVAC tech to check the heat pump's reversing valve solenoid.
HEADS UP Ignoring this and trying to reset can damage expensive heat pump components. If you didn't install it yourself, get the original installer back to verify the wiring and configuration.