The “Scan Scam” is yet another way for you to be separated from your hard earned money!
Since the late 70’s early 80’s manufacturers have been providing drivers with a warning system for their vehicles malfunctioning control systems. Over the years vehicle control systems and their “on-board” self-diagnostics have become very complex. Every aspect of a vehicles engine, transmission, climate control, accessory and safety 
systems are at the direct control of a management system. Many vehicles have multiple electronic control units and some European models can exceed 40 onboard processors on a network.
Every vehicle manufactured since 1981 has some form of control malfunction warning system for the driver of the vehicle, usually a light on the dash somewhere. The warning may read something like; check engine, service engine, maintenance required or something similar. The 
particulars change from vehicle to vehicle and year to year, but the warning system is there. If unsure about the warning system on your own vehicle, look at the vehicles owners’ manual or ask an ASE Certified Shop or Technician.
Every driver should be familiar with the warning system on his or her own vehicle. All the dash mounted warning lamps will illuminate any time the key is in the run position and the engine is not running. If the vehicles diagnostic system sees trouble while the engine is running, the warning light illuminates to warn the driver, and a bit of information is also stored to help a technician begin to sort out the problem. This bit information is known as a “trouble code” and it is extracted from the vehicles control system by various methods usually referred to as “scanning” or “retrieving codes”.
Some Convenience Oil Change Providers offer code retrieval to customers for a fee. Save your money! Parts stores have begun to scan for free to help bolster parts sales, the only guarantee being that you own the parts you buy whether they fix your problems or not.
People have always liked to think that it’s just a matter of “plugging it in” and it’s all diagnosed and the repair is cut and dry. Vehicle control system on-board diagnostics and Trouble codes they provide have improved over time, especially since 1996 with OBD II (On Board Diagnostics Second Generation), but are far from perfect. Frequently the cause of a “Service Engine” light’s appearance is a faulty component. A code is set that indicates an abnormality with a particular system or component, the indicated item is replaced or repaired and all is well. That’s how it works ideally, but often there are intermittent problems, multiple trouble codes, false codes, or no codes present. Here’s where skilled repair saves you money.
Normally any repair of a vehicle’s control system would require scanning and using manufacturers outlines for confirmation of trouble codes known as “diagnostic flow charts”. These multi-level checks are the only way to verify the validity of a trouble code, short of experience, luck, visual clues, or replacement of parts. Herein lays the difference between a technician and a parts changer. Electrical parts can be very expensive and are non-returnable; once plugged in…they are yours whether needed or not. Parts changers could run up a pretty big bill before they might randomly hit upon the right answer.. Controller failures, wiring and connector problems, multiple failures, are some examples of problems not to be found by changing parts.
The bottom line of all this is to say that unless you don’t trust your mechanic, you are going to try to fix the vehicle yourself, or you want to take your baby to some “parts changer” and tell him how to fix your car, the vehicle needs to be scanned by the party who is ultimately responsible for making and standing behind a proper repair. Why pay for this retrieval operation twice, you will probably (and should) be charged for that service by the actual repair provider. The fact that you have some data stream or trouble code information is not going to save you any money or fix the car. All the information the average driver needs is on the dash…. for free! I maintain that this service of trouble code retrieval is a waste of the consumer’s time and or hard earned money!
So when your vehicle’s warning system tells you that your vehicle is not happy… don’t waste the money to have your vehicle “plugged in” by anyone that is unable to offer professional, guaranteed repair.
