Successful diagnosis is the result of an organized diagnostic approach. There is no magic wand available to wave over the hood that will instantly pinpoint the problem. OBD-II trouble codes offer only a clue as to what may be causing a particular problem with your car. An OBD-II trouble code, once extracted from your vehicle’s onboard computer, should be looked up in a chart and used in conjuction with other data such as symptom observables, history of the problem in question, TSB’s (Technical Service Bulletins), etc in order to reach an accurate diagnosis. A single symptom can be caused by numerous components on the vehicle. An accurate diagnosis should isolate the failed component. Sometimes however, it is more cost effective to replace the most suspect part and then spend the time or money on further diagnosis. Only you will be able to determine at what point this is.