I was on my way to Florida and had to swing into a Hyundai Dealer in Birmington, Al. because my 2002 SantaFe died all of a sudden on the Interstate ; fortunately, it re-started after a few minutes but ran rough. The Service Dept. read the Engine Code and it indicated the Mass Airflow Sensor was defective ; the Service Advisor said it was shorted and the installation would run a few hundred dollars and that they had it in stock. I was skeptical , so i declined the repair and paid their $89 diagnosis fee . When i got some distance from the Dealership, i pulled the intake hose from the MAF Sensor housing ...and low and behold ... i immediately found the problem : A small piece of debris had lodged itself on the inlet screen . I removed that and the engine ran normal again and has not been a problem since. Obviously, the Service Dept. was more interested in making profit on parts changing than anything else.
Im sure its a scenario thats repeated many thousands of times each day in America .