Basically P19FE means your battery coolant pump is not operating at the speed it is being commanded (specifically slower or not at all)
So the dealer tech will follow the diagnostics that looks for circuit faults that might cause this or mechanical issues with the pump itself which would result in it needing to be replaced.
Should be pretty easy to diagnose and repair
There is really no potential worry as far as the battery itself is concerned as if it's cell temps were approaching/exceeding safe thresholds the system would first go into PPR (propulsion power reduced) or even shut the propulsion system down to mitigate cell damage due to excessive heat.
Don't think we've seen this DTC reported here on a Gen2 before so please keep us updated!
Wellcome to GM Volt.com
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