I have '17 cx 5 , recent bumper change and the SCBS system disable warning comes on and resets itself after a cycle. I've been to windshield shop to have the sensor recalibrated but pls still exists , garage tell me there's no sensor in the bumpers .

 

The sensors are located near the rear-view mirror and the front Mazda badge on the grille.
If your front bumper was hit that could impact the grille sensor.
Common issue is if they get dirty and/or covered they don't work and you'll get an error message.
Happens to me on occasion here in the Northeast during winter during snow/freezing rain road conditions and has also happened with fog and frost.