Mystery alarm after impeller change 2000 GX 225

[v-hullwaverider163]

I swapped out the impeller on my 2000 Glastron GX 225, but now I get an alarm when I start it up. Oil pressure is good, the engine isn't overheating, and the reservoir is full.
Could this be a water flow thing or did I mess something up when I put it back together? I don't see any leaks or obvious problems, but the alarm is making me worry.
Any ideas? I'm hoping I don't have to take everything apart again.

 

[autobotsss]

It's possible it's a sensor that's not seated right or maybe the hose from the pump got kinked. Before anything you can try to double-check the water pickup line and make sure the impeller fins went in the right direction.