PBY patrols used successfully in Midway
The Yanks put out PBY patrols at Midway when they knew the Japanese were on the way and the Japanese fleets were detected.
So yes, PBY patrols at Pearl Harbor would have raised the alert, but there were other readiness issues. Assessments of Pearl Harbor have suggested that loss of life would have been considerably greater had the battleships been sunk in open ocean.