Did you figure out how to get it to calibrate? Twice I needed to turn off the auto mode (670g) and then turn it back on again for it to calibrate and switch into auto mode. I’m not sure this will help you or not – it WAS accepting calibrations for the sensor to function, but it wasn’t accepting them for the purpose of the pump using the sensor readings to adjust insulin delivery.
I was using a Dexcom G5 for almost 2yrs. Last April I got the 630G pump with the Enlite sensor and it was a joke. Last week I started on the 670G with the Guardian sensor
So far I have found the Guardian to be more accurate. I am scheduled to go to auto mode next week.
I have not ever used the Dexcom but I am using the Guardian 3 sensor and love it. I find it mostly very accurate. What I don’t like is auto mode. I had way better control over my sugars on Manual mode than I do on the “closed loop” system. Overall I am happy with medtronic, just finding auto mode to be a pain in the ass. And I am not accustomed to having higher sugars all the time.