From time to time we will get a call into the shop from a customer asking for a Diagnostic for their car. We will always ask the caller what is going on with their car in order to understand the issue that they're concerned with. We get everything from a warning light being on to issues with how the car runs and even complaints about a strange noise their vehicle is making. Many times the caller has the impression that we have machine or tool that we can plug into the car that will tell us all of the car's problems. Unfortunately, there is no such tool.
While today's modern vehicle has many sensors, computers and miles of wire, it can be very complicated to get to the root cause of a problem. The good news is that while there is no magic box that we can plug into your car, our mechanic has the tools that can communicate with the modules on your car. The tool, known as a scan tool, can give us information as to where the problem occurs. Many times a trouble code will be stored. Many customers believe that the trouble code tells you exactly what is wrong with the vehicle, but this is not the case. Think of the trouble code as a ZIP code. If you give someone your ZIP code, they may know the area in which you live, but they don't know where your house is. Your auto technician will use the trouble code along with his knowledge of the system and test procedures as well as meters, gauges, and even a lab oscilloscope to determine what the root cause of the problem is.
The best thing to do when you have a problem with your car is to tell your auto service mechanic what the issue/symptom is with all the supporting information that you can. Resist the temptation in telling them what you think the cause of the problem is. Don't ask for a Diagnostic. Once the professional gets your information about the issue/symptom ,they will offer what test(s) will be needed.
Fred Hules II is the owner of Tech 1 Auto in Peoria. He is an ASE Certified Master Auto Technician and recipient of the 2015 & 2017 NAPA/ASE Arizona Technician of the year award. Listen to Fred host Automotive Know How radio show every Monday at 4 PM on 1100 KFNX.