Diagnostics is a wide ranging discipline which can often require specific expertise. If your garage genuinely does not have specialist knowledge in-house, partnering with an expert who you can call upon for those difficult, seemingly impossible to diagnose jobs could prove to be a wise investment helping your business formulate a reputation of being able to fix practically any fault.


Basic diagnostics should take place on any job, even the simplest, for example, a tyre which continues to deflate but does not have a nail stuck in it, requires a straightforward diagnostic procedure where the obvious is explored and systematically ruled out until the conclusion is reached such as corrosion on the wheel.

The same three processes should be followed for any diagnostic procedure from the simple outlined above to the most complex: find the evidence, evaluate and rule it out and repeat until the fault is found.

Whether a computer engineer is trying to diagnose an issue with a laptop or a police officer is piecing together a crime scene, the process remains the same. By keeping the series of steps logical and simple and escalating a notch at each stage, it is likely the evidence will lead the technician to the correct conclusion.

The rule of thumb is: don’t overlook the obvious. Blown fuses, for example, can often be at the heart of many a fault which can appear complicated at first sight.

Look for evidence, evaluate what you find and move on in a different direction if the fault persists. Diagnostics is about looking for clues in order to build up a bigger picture until you have all the pieces in place and the puzzle is complete.

We were told one story of how a specialist was called in after six garages tried and failed to identify the fault with a vehicle which had been taken to the first workshop for a new gearbox. The hapless owner had spent around £1,000 in total as different mechanics attempted to diagnose the fault. By the time it came into the hands of the specialist, the series of ‘fixes’ undertaken by the other garages had to be put right. The fault itself took the specialist 20 minutes to locate and repair, it was an internal fault in the electric power steering module which had short circuited the car’s CAN-BUS network and prevented all the systems from communicating with each other and therefore ceased to operate.

If you genuinely can’t fix the problem, don’t spend your time and your customer’s money fixing faults you think it could be, find a local specialist and call the expert in when you need them.

Most workshops have a diagnostic machine which is simply connected to the car and generates a number of codes. However, the diagnostic machine cannot be relied upon in its own right, it provides an indication of where to start, but the real work is in the interpretation and that comes down to the skills and experience of the person taking the next steps after the diagnostic reading.

Another story told to us was a motorist who was charged £35 for a diagnosis and was given the series of codes which the equipment generated. It was obviously a meaningless exercise and even an experienced mechanic would need to undertake additional tests to identify the cause of the fault and, of course, put it right.

A specialist who uses CarVue estimates he has an impressive 95% success rate of diagnosing and fixing faults which outfox many other mechanics. However, it is usually financial restrictions dictated by common sense and the value of the vehicle which makes diagnosis and fix not a viable option.

We asked automotive electrical and mechanical engineering Jonathan Fry for his top diagnostic tips:


  1. S.T.O.P. – Stop, Think, Observe, Plan.


  1. Keep it simple.


  1. Don’t overlook the obvious.


  1. Don’t guess it, test it.


  1. Don’t take anyone else’s word for it.


CarVue is a revolutionary cloud-based application for independent workshops, garages and mechanics. It’s a simple and smart app that removes the need for expensive servers, software upgrades or training to run an automotive business. With a simple web browser a workshop can be managed from any device, any time and from anywhere. Find out much more and sign up for an obligation free trial today at www.carvue.com