WHY DO I HAVE TO PAY DIAGNOSTIC FEES FOR MY CAR?

29/01/2020

“Just the other day I visited an orthopaedic surgeon for my third post-surgery exam. The surgeon asked me a few questions, moved my kneecap around a bit, flexed my leg and told me everything was fine. Forget the fact that my knee was still sore. That, he said, would resolve in time. After waiting more than an hour to see the doctor, I saw him for less than five minutes, and all he said was, "Looks good". I left frustrated with the residual pain in my knee and the seeming waste of time in my doctor’s office.

Frustrated as I was, I never once thought that the surgeon should not be paid for his time. Months earlier I visited that same office with a complaint of pain in my knee. The doctor performed an exam and ordered an MRI. When the test results were in, I visited again so that he could explain what he found. He got paid for those visits too. See, while I was quite familiar with the pain I was experiencing, I could not have interpreted the results of the MRI myself. Neither could I have planned a course of action. I needed the surgeon’s years of training and expertise (not to mention the MRI machine) for an accurate diagnosis”.

With that all said, have you considered the costs associated with the shop to which you are delivering your vehicle? Besides the actual time a technician spends looking at your car, there is a mound of overhead expenses just to keep the shop doors open and lights on: a lease, insurance, utilities and more. There are hundreds of thousands of dollars of specialized diagnostic and repair equipment. And there are trained technicians, each with thousands of dollars of tools and years of experience. What you are paying for is quality service. And an accurate diagnosis is just as much a service item as if the technician had manually repaired or replaced a part on your car.

So why would you expect that service to be “on the house”?

The trouble with trouble codes

One of the reasons many of us have a tough time swallowing diagnostic fees at a repair shop stems from a common misconception. Modern vehicles are equipped with a network of computer modules that continuously monitor vehicle systems. When something goes wrong in a system, a computer module stores a Diagnostic Trouble Code (DTC) and often alerts the driver through a warning light on the dashboard. If the Supplemental Restraint System (SRS) that controls the airbags has a problem, the airbag light on your dash turns on. If an oxygen sensor goes bad, your check engine light comes on. Our cars are smart enough to tell us when something goes wrong.

But that is where the misconception begins. It is true that when a special scan tool is connected to a vehicle’s data link connector, those trouble codes stored in the computer can be read. So, many folks believe that by simply plugging in and reading the scan tool, a technician can easily diagnose an issue. How hard can that be? And how much time could it possibly take? The computer is doing all the work. Right? Wrong.

You take your car in for service because your SRS warning light is on and because you correctly assume that your airbags might not be operational. A technician plugs in a scan tool and finds a DTC leading to a specific circuit in the system, say, the passenger seat belt retractor. Now what?

The popular notion is that the technician’s job is done. Diagnosis performed. But the truth is it has only begun. What started with a customer complaint (“My airbag light is on”) led to a diagnostic scan. But that is still the beginning of a diagnosis. The technician still does not know what the problem is, only where it might be found

Pinpointing the problem

Diagnostic scan tools do not simply spit out a diagnosis. So what does a diagnostic scan show? Scan tools read and display the DTCs stored in the computer. But the DTC is a code: a letter and a few numbers. P0135 , P0340 and B1881 are examples of DTCs for (respectively) a faulty oxygen sensor, camshaft position sensor circuit, and passenger seat belt pretensioner. In each of these cases, the DTC does not imply a problem with that component specifically, only that there is a fault in the circuit in which the component resides. The DTC does not give a specific diagnosis any more than an MRI tells a patient what is wrong with his knee.

Once a technician receives the DTC from a scan tool, (s)he still has to perform a series of pinpoint tests to determine the exact cause of the fault revealed by the code. In the case of an oxygen sensor, the correct sensor needs to be identified (cars often have four oxygen sensors). With a camshaft position sensor fault, the problem could be with the sensor, the wiring, or even the powertrain control module. And in our SRS “airbag light” example, the fault could lie with the pretensioner, the wiring, or a bad ground. A technician needs to “pinpoint” the problem beyond a simple scan.

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