It could be the bearings in the pulley on the belt tensioner are worn; but your mileage is low, pulleys normally last near 80-100K miles. Do a visual inspection, if serpentine belt is original it's due for change.
With belt off or belt tension relieved you can readily spin the pulley to check for play in the bearings.
I can't make sense of the fault code, hmm...
Good luck/Bill
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