Doing Your Own Diagnostics Is Still Important

Order Reprints

As a shop owner today, things are a lot different than in years past.

Remember when you could have a customer describe their problem to you, your mechanic could drive the car, and right away he knew what the problem was? Remember when your mechanic could identify a misfire during a drive, or a bad plug, wire or points? Today, a complaint that feels like a misfire could be any number of other issues.

Back in the day, a mechanic was just that, a mechanic. There wasn’t much to it. The cars were simple to work on, with no computers, no fuel injection, etc. Today’s cars are very complex, with multiple computers and miles of wiring. Today, we rely on highly educated and trained technicians, not the mechanics of yesteryear, to properly diagnose and repair these vehicles. But we also rely heavily on information service providers like Identifix and Mitchell 1, and peer networks, such as iATN.

The challenge is striking a balance between using those services and maintaining the skills required to properly diagnose vehicles. Otherwise, such services can become a crutch and lead to inefficiencies. 

Let me explain with an example from my shop:
The service advisor dispatched a vehicle to a new technician with a drivability complaint and a failed smog check. Within 30 minutes, a test drive had been performed, a code was pulled (P0304), and an iATN diagnosis had been found. The tech said it was a bad No. 4 coil. According to iATN, this was a common problem.

We let him put the coil on the car, but guess what? It didn’t fix the car. I intervened and asked the technician what he thought. He suggested that the plug might be bad.

I told him a lot of things could be bad, and I asked to see his diagnostic worksheet. I explained the diagnostic procedure in our shop to him and the reason for it on the day he was hired, so I was sure he followed my directions. Needless to say, he did not. There was no diagnostic worksheet, no flowchart, nor any type of documentation whatsoever.

I spent the next hour or so walking him through the diagnostic process, step by step, and ultimately confirmed a diagnosis, which happened to be low compression on the No. 4 cylinder due to a leaking exhaust valve. I explained that only basic testing was needed for this diagnosis and there was never a need to use a hotline or iATN. The technician now understands the process and what is required for a complete and accurate diagnosis, and won’t run to a service provider or network without covering the basics first.

Staff Graphic

So what is standard procedure in the industry? How are you handling these situations? Here are some ideas that might help:

1. Have a specific diagnostic worksheet for each area, such as drivability, air conditioning, brakes, etc. This will help your technician document an accurate diagnosis for the service advisor and it creates a uniform diagnostic process that saves time and money.

2. Train your current and new technicians on the diagnostic process and procedure. This will help eliminate confusion and build solid, confident diagnosticians.

3. Train your technicians to know when it is the right time to use resources outside of basic testing. Use networks and service providers only when needed, not as a substitute for a lack of knowledge.

I think repair services and networks are some of the best resources we have. We use them quite frequently in our shop, but you must know when to use them to your benefit, or they can end up being counterproductive. These aides should not be a replacement for proper training and education, but an accessory to it.

B.J. Lee has worked in the automotive repair industry for more than 30 years. He is an industry consultant and trainer for and owner of Stellar Performance Inc. in 29 Palms, Calif. Contact him at

Recommended Products

2016 Ratchet+Wrench Shop Performance Survey: Complete Report

2017 Ratchet+Wrench Shop Technology Survey: Complete Report

Related Articles

Your Good Reputation Is One of Your Most Important Assets

The Average Shop Experience is Still Very … Meh

You must login or register in order to post a comment.