Why do shops charge a diagnostic fee?
Service shops charge a diagnostic fee because it requires a little extra time to communicate with the car’s on board computer. Every vehicle manufactured since 1980 has some form of a computer; as the years have gone by and technology has become more complex, many of these cars now have 2 or 3 main computers. The time it takes to communicate with the vehicle, and to research the information provided, takes longer than it used to.