Afterboil issue?
 

Does anyone know how/what turns on the fans and afterboil pump when you turn the car off? I have a 2003 cts that sometimes boils out. Had the coolant flushed due to oil mixed, ECT sensor changed cuz the fans weren't coming on and now they work. The pump itself works because I've tested it but the fans turn off and the afterboil pump doesn't come on when I turn the car off. Where is the sensor for this or how is it activated?? Thanks!