OEMTOOLS 24444 Coolant Vacuum Refill Kit, Coolant Pressure Tester Kit, 70–110 PSI Working Pressure, 5 Bushings, 1 Tapered Cone Adapter, Vacuum Leak Detector, Pressure Tester for Coolant System

Have you scanned it to see if there are any codes? Do that first and see if it's a sensor issue. Who installed the water pump? How did they go about filling the coolant? Since it presumably has fresh coolant in it, I would try one of those elevated coolant funnels that screws on to the reservoir cap. https://a.co/d/02fIhYLN. You can fill it with coolant much higher than the reservoir to force air out of the system. Hook it up, fill it up, start car, heater on high fan on low, let the car heat up and see if you get any major bubbles out. If that doesn't work I would try doing a proper vacuum bleed. Drain all of the coolant and start over. You'll need access to a decent size air compressor. https://a.co/d/00adpZ2o. This is the fool proof way to make sure there is zero air in the system.