What Does It Mean To Diagnose a Vehicle?
In order to understand a diagnosis we need to look at the definition of a diagnosis: An analysis of the facts or problems in order to gain understanding and aid future planning; to identify the nature or cause of a phenomenon; an opinion or consensus reached through analysis. This leads us to look at the definition of analysis: A detailed examination of the elements or structure of something.
So how does this apply? If a vehicle is performing poorly or has a warning light on the dash, a technician cannot just scan the computer(s) of the vehicle retrieve codes and tell you what is wrong with the vehicle. They need to pull all the data, this gives them detailed information about when and how many times an event has occurred. They have to perform pinpoint testing on the system (s) involved. They retrieve and analysis what the specifications of the components and system(s) tested should be at and what they are currently operating at to figure out what is causing the problem.
This procedure takes a highly qualified and trained technician, with professional grade diagnostic equipment, and the software or connection to vehicle information to get the comparison information needed to perform the analysis. This procedure can take a few hours to complete, especially if the problem is intermittent and does not happen every time you operate the vehicle.
To have a professional properly diagnose a vehicle there is a charge associated with that. As the cars we drive become more automated and complex this procedure will become more expensive and complicated. It is much more cost effective to pay to have your vehicle properly diagnosed then to guess at replacement parts and perform repairs that are not needed or do not fix the problem. Happy Motoring!