From the earliest days of the commercial sale of the automobile, it has been obvious that maintenance is required to keep automobiles operating properly. Of course, automobile dealerships have provided this service for years, as have independent repair shops and service stations. Until the early 1970s, however, a great deal of the routine maintenance and repair was done by car owners themselves,
... [Show full abstract] using inexpensive tools and equipment. However, the Clean Air Act affected not only the emissions produced by automobiles but also the complexity of the engine control systems and, as a result, the complexity of automobile maintenance and repair. Car owners can no longer, as a matter of course, do their own maintenance and repairs on certain automotive subsystems (particularly, the engine). In fact, the traditional shop manual used for years by technicians for repairing cars is rapidly becoming obsolete and is being replaced by electronic technician aids.