I have a 2019 GMC Acadia SLT-1 V6. I have recently had my car at a dealership for another issue out of my control and was asked about the message I have seen pop up occasionally and go away. "Steering Assist Reduced Drive With Care". When that code does come on my fans run all the time and high and my AC doesnt work and blows warm air. They told me they recommend to replace my thermostat which is in the water inlet assembly and quoted me $725 to do the work. I called the dealer that I usually go to and asked what it would cost me to replace the thermostat and they told me $515 and change out the door. They did inform me that if I wanted them to diagnose it, that it would cost me $155, and that if that was what they found it would be $155+$515 to do it but if it did not fix the issue I wouldn't have to pay for it since they misdiagnosed it. Well since they know me they said that I can bring it in and they will diagnose it and if they find the same issue they wont charge me the $155. I had the dealership that told me this issue print out what codes were being thrown, it is the P0128 and U0401, I am not sure what the U0401 is about but I am guessing it has to do with the other code??? Also, I have read that sometimes it can be the sensor that goes bad and it can be replaced. Should I just go ahead with having my normal dealership replace the thermostat?