Inspection & Diagnostics

Diagnostic tests can reveal problems within a car’s engine, transmission, exhaust system, brakes, and other major components, as well as performance issues with the fuel injector, air flow and coolant, ignition coils, and throttle.
However, a common misconception about car diagnostic tests is that technicians can use code-reading tools to determine the exact problem that triggered the check engine light. In reality, the code tells technicians which engine or component parameters are out of range, but it does not detail the cause of the problems. That’s where the good old human brain comes in handy, as the technician uses experience and expertise to diagnose the underlying problem.

Before the emergence of car diagnostic tests, identifying problems was time-consuming and expensive, especially considering car owners only brought their cars to mechanics after a breakdown or other severe malfunction. Now, computerized car components can detect problems long before they cause a breakdown. Diagnostic tools can also check a car’s computer system for manufacturer notifications and stored information about the car’s history, giving technicians a complete picture in order to perform the best repair possible.

You don’t have to wait for the check engine light to get a car diagnostic test. If you hear or feel something “off,” mechanics can use diagnostic testing to uncover the problem. However, many technicians recommend taking your car in for a diagnostic check at least once a year, which will uncover minor problems that can’t be seen or heard (and that won’t trigger the check engine light).

Diagnostic testing is also a useful tool when you’re checking out a used car. Both private sellers and professional car dealers should agree to a diagnostic test before you commit to buying, and if they don’t, that’s a sign you should walk away from the deal.