I want to share this experience because it may help another driver or owner-operator avoid chasing the wrong repair. My 2021 Peterbilt 579 started showing an Adaptive Cruise Fault / Inspect Radar warning. The dash kept beeping, cruise control was disabled, and the truck made it look like the radar system was the main problem. At first, that is where the attention goes: front radar, sensor blocked, dirty radar face, calibration, wiring, etc. But the radar was clean. Nothing was blocking it. The system would still detect and beep, so it did not act like a completely dead radar. The problem was more confusing because the warning would show up worse in wet weather and sometimes right after the air dryer purged. That was the first clue: this was not only about the radar. :::