All automotive service personnel should avoid the shotgun approach to automotive diagnosis.
Usually, it's counterproductive for reasons that owners, managers, salespeople and technicians often overlook.
In case you're not aware, the shotgun approach is the basic parts-changing technique where techs gamble that throwing one new part after another at a vehicle's symptoms will eventually fix it—sooner or later. To be fair, this ham-handed approach does fix some vehicles.
But based on my shop experience, the old shotgun method is fixing fewer and fewer problems today.
I'm hardly alone in this opinion. For example, many dedicated technicians I meet in my seminars describe diagnosing vehicles loaded with new parts that didn't solve a customer's problems. Rather, a professional, thorough analysis reveals a problem the parts-swappers missed entirely.
“Shotgunning” isn't difficult to understand. Suppose a vehicle comes into the shop with a particular symptom or set of symptoms. Experience suggests—only suggests, mind you—that replacing sensor X eliminates these symptoms. Or, imagine that an onboard computer set a trouble code for sensor X. In these situations, the parts-changer or shotgunner replaces sensor X in hopes of fixing the vehicle on the first try.
Whenever replacing sensor X doesn't do the trick, they're likely to throw another part at the problem. (Yes, many parts suppliers will take anything back if it doesn't fix a vehicle.)
Note that a shotgun approach may originate in the front office or sales desk. Other times it is born and grown back in the service bays. In many instances, the parts-changing approach is a collaborative effort between the front and back ends of an auto service facility.
For example, an owner, manager or service salesperson may have usurped part of the technician's role. Over a period of time, they've decided when a tech should replace sensor X—damn the diagnosis.
But in other cases, unqualified workers are masquerading as professional techs. They are shotgunning jobs simply because they lack the knowledge and training to diagnose them correctly. When they throw enough parts at a vehicle, the law of averages suggest they will eventually succeed some of the time.
They may succeed often enough to convince the boss that they're actually capable automotive repair people.
To me, the shotgun approach is simply fraught with problems. First, it breeds a false sense of security among service personnel that swapping parts is more effective than methodical diagnosis. Experience shows that it breeds unrealistic expectations on both sides of the service counter.
Indeed, this technique may succeed some of the time, but it also distracts everyone from the need for genuine diagnosis—as opposed to changing parts recklessly. A true, methodical diagnosis does take time but also yields the correct answers.
These, in turn, produce a job that's fixed correctly the first time.
Ultimately, fixed right the first time is the customer's goal and first concern—and is the key to meeting or exceeding a customer's expectations. On the other hand, reporting that replacing parts did not fix the car telegraphs that you're just another cluster of clowns in the auto repair circus.
Second, the less frequently that technicians practice a step-by-step diagnosis, the less skill they acquire with it. The more often they practice methodical diagnosis, the more familiar and comfortable they become with it. Familiarity and comfort breed additional confidence and speed on all diagnostic jobs, simple or complicated.
Finally, an accurate diagnosis has value. In any field of endeavor, knowledge and skill have value because they yield results. The same is true in automotive diagnosis and repair.
Charging for diagnosis brings income you sorely need and likely would not have gotten otherwise.