P00B7 error code help

Currently fighting a P00B7 (ECM-Engine Coolant Flow Low/Perf) engine light. I've seen several threads mention a leak in the EGR system. Truck is currently deleted with Wheeler's kit and I have tiny leak at the reroute plate. Like just leaving blue gunk around one side of the mating surface. My plan this weekend is to reseal and correct the leak, but my question is how big of a leak does the ECM need to throw the P00B7 code or is there something else worth looking into?

Does the engine have a coolant flow sensor inside the return inlet on the overflow tank? I've also seen several threads mentioning the level sensor failing but the truck isnt going into limp mode, or and kind of weird power reduced mode. Coolant is up to the full mark on the overflow tank.