Skip To Content
Special Offer! Click for $25 off your first visit.

Let's Talk Lunch - The "Free" Diagnostic

European Auto Repair Ann Arbor

Uh-oh! That dreaded “Check Engine Light” illuminated on your dashboard, and you immediately recall seeing a “free diagnostic” sign in the window of your neighborhood auto parts store (or auto shop). And while you definitely do NOT want to pay more than what is necessary for proper vehicle repair, those prominent lines of conventional wisdom are also circling around in your brain…

–          “You get what you pay for”

–          “There is no such thing as a free lunch”

–          “If it sounds too good to be true, it probably is”

The logic here is simple and truthful, but when it comes to vehicle diagnostic trouble codes (DTC), a lot of drivers are lured into the “free diagnostic” facade which is not only misleading, but in many cases couldn’t be farther from the truth.


european Auto Repair Ann Arbor
Our Snap-on Verus Diagnostic Tool

If you’re not paying for a diagnostic, then you’re not going to receive one – at least, not for free anyway. It is a very common practice for auto parts stores and some auto shops to offer a free code reading. (ArborMotion will do this for our customers as well, if requested). There is a lot of public misconception though as far as what these codes tell the technician outright about the particular issue that your vehicle is experiencing. A code on its own is NOT a diagnostic; it is typically just the beginning of the problem-finding process. Sebastian Gaeta, owner of ArborMotion, recently illustrated how the trouble code diagnostic process works…

Think of your vehicle’s many systems like looking at a map of the United States and the issue with your car is located inside a house that could be anywhere in our country. By scanning for the code, it will narrow the issue down to which “State” the house is in.  At that point the real work begins because now the technician uses his many years of experience and our high-tech diagnostic equipment to find “the city,” locate “the neighborhood,” work to isolate the “street,” and then finally pinpoint the “house” where the problem lies. Even then there could be more work to do depending on the particular issue. What all of this means is that if someone is diagnosing your problem with a simple reading of a code, then at best it is a guess which is why it is free, whereas a diagnosis pinpoints the exact issue.

european Auto Repair Ann Arbor
Mike Pisarski, Audi & Volkswagen Master Tech

For example, let’s say that we scan your vehicle and receive a “Cylinder Misfire” code. According to Mike Pisarski, ArborMotion’s Audi and Volkswagen Master Technician, this code could mean that a spark plug went bad, there is carbon on the valves, low fuel pressure, the exhaust is plugged, there is a bad ignition coil, etc.  Consequently, how can you pinpoint the exact problem that your vehicle is experiencing based solely on the scanned code? Well, you can’t! In order to fix the issue, you must FIRST diagnose it by running additional tests. And your best bet as far as an accurate diagnostic is finding a technician that specializes in your vehicle’s make, and taking advantage of his/her years of knowledge and experience in order to find and repair the problem.

european Auto Repair Ann Arbor
At left is a readily available and inexpensive code reader. To the right is the Snap-on Verus diagnostic tool that we use here at ArborMotion.

The “free diagnostic” that you will likely receive from the auto parts store is nothing more than a guess based on the scanned code, and what they assume could be the problem. They will sell you a part/service that “should” fix the problem, and if it doesn’t, then they will suggest another part/service. (Yes, this seriously happens every day). A trouble code may point to a sensor, but that does not always mean the sensor is bad, but they’re probably going to sell you one regardless. Consider this scenario from Dan Edmunds, director of vehicle testing for

My wife’s car started running poorly and there was a Check Engine light. My code reader detected a code for the Cam Angle Sensor. I thought about buying the sensor and installing it myself, but if I had, I would have wasted time and money because it turned out that the sensor was fine. Instead, mice had gotten under the hood and had chewed some of the wires leading to it.

Furthermore, the part that you were talked into buying may be of inferior quality. Aside from the fact that installing this part may not fix the original problem, it could also cause an entirely new problem!  

BOTTOM LINE – a “free diagnostic” based on the code message alone is not a diagnosis at all, and it could end up costing you unnecessary parts and repairs under the guise of “free diagnostic.”

european Auto Repair Ann Arbor


The certified technicians that work on your vehicle do not (and honestly should not) work for free. The time that they spend diagnosing the problem(s) with your car are hours worked, and their education and equipment used were not free either. And if you are at an auto shop that insists that they give “free diagnostics,” beware of marked-up part and/or labor costs in the repair estimate. Many shops will just “package” the price of repairs into one lump sum in order to avoid you seeing what charges are specifically being allocated to labor, parts, etc. In many cases, that “free diagnostic” time is made up for in this bundled price tag.

Admittedly, if you have the vehicle’s problem diagnosed at this shop but choose not to have the repair done, then the shop will be out that diagnostic time. However, these shops are fairly confident in taking the chance that the customer will choose to have the repair done, because they realize it is the customer’s goal to avoid diagnostic fees. That same customer will then assume that a shop that doesn’t charge these diagnostic fees will be “cheaper” in the repair, but the fact of the matter is that the shop DOES charge these fees – they just call it something else or hide it all together.

european Auto Repair Ann Arbor
Certificates of technician certification at ArborMotion


There just simply is no such thing as a free code diagnostic. The trouble code may give the technician an idea of what could be going on with the car, but if you wish to repair the problem in the most efficient and cost-effective manner, bring your vehicle in for a proper diagnostic from a certified technician. With an estimated 10% of vehicles on the road with “Check Engine Lights” on, it’s obvious that drivers try to do their best in order to avoid such repairs. However, it is best to have these warning lights diagnosed and taken care of as soon as possible in order to help avoid much more costly problems and repairs down the road.

Carfax Top Rated Shop 2019 Carfax Top Rated Shop 2020 Carfax Top Rated Shop 2021 Carfax Top Rated Shop 2022 Carfax Top Rated Shop 2023 Automotive Service Excellence Nextdoor Neighborhood Favorite 2019 Nextdoor Neighborhood Favorite 2020 Nextdoor Neighborhood Favorite 2021

We Handle Vehicle Maintenance & Repair in Your Area!

Volvo Repair VW and Audi Repair BMW and MINI Repair Mercedes Repair Porsche Repair

Providing Excellent Domestic and Import Repair & Service For The Following Areas

Request Service 734-761-1088