Wierd.
If the ECU is popping out codes & the codes point to a sensor then the sensor is probably shot but, like you, I think it begs of something else deeper going on. Lousy ground perhaps? Battery issues? This car wasn't under water, was it? No accidents in its past?
As long as the car is still under warranty keep taking it back until it's squared away but I would try to find a different service department first. If your gut feeling is that the tech. is an imbecile then go with your gut & find someone else.
Good Luck, Rude!!