Car Diagnostics Everything You Need to Know | CCM Blog

What Are Car Diagnostic: Everything You Need to Know

Diagnostics are a pretty common job for us, with our teams running multiple diagnostics tests each day. But without being in the trade, it’s common not to know exactly what a diagnostic test is. We’re here to help answer any burning questions you have, as well as run through exactly what happens during a diagnostic test.

What are car diagnostics?

A vehicle diagnostics test is a way for technicians to get a detailed report on any issues that may be happening in your vehicle. Cars contain a huge amount of software and computing these days which can report on any faults. Having these tools can save a huge amount of time in finding what may be the cause of the issues you are facing.

What parts of a car can be tested with diagnostics?

Because of the multitude of sensors, processors and microchips across your car, diagnostic equipment can reveal many problems. These include but are not limited to:

  • Engine
  • Transmission
  • Exhaust system
  • Brakes

Plus, performance issues relating to:

  • Fuel injectors
  • Airflow
  • Coolant
  • Ignition coils
  • Throttle

A common misunderstanding with diagnostics is that you are able to see the exact issue instantly. Unfortunately, this is not the case. What we actually receive is a code telling us which parameters are out of range. This is where our technician’s experience and expertise come in to diagnose the underlying problem.

What are the benefits of a car diagnostic test?

Before diagnostics tests were readily available, identifying problems and their causes was a time-consuming process. This was even trickier for mechanics when the car had broken down suddenly. Thankfully, computerised systems can detect problems before they cause a breakdown. Diagnostic tools are able to access the car’s computer system for stored information regarding the car’s history and manufacturer notifications. This provides our technicians with a bigger picture of the issue at hand allowing for a quicker solution.

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When do you need diagnostics?

There are lots of reasons why you might book your car in for a diagnostic test. Sometimes it’s the engine management light, it could be a new noise that had just appeared, a loss of power or slipping gears. There are so many different reasons to book in for diagnostics! Realistically, it’s recommended to have a diagnostic test each year. This can uncover any minor issues before they get worse.

How do you perform a car diagnostics test?

Let us just say, that diagnostics is not just “plugging it in”. We’d love for it to be that easy but there’s a lot more to do to get an accurate answer!

Here’s a step-by-step breakdown of the diagnostic testing process.

  1. Gather information from the customer about the issue/fault
  2. Road test to see if the issue occurs and get a feel for the vehicle
  3. Fault code scan
  4. Visual inspection
  5. Vehicle serial data
  6. Technical service bulletin
  7. Basic system checks
  8. If fixed, another road test to confirm. If not fixed we’ll contact the customer for more investigation hours

1. We ask you for as much detail as possible relating to your issue

The more information you can share with our technicians, the easier it will be for them to resolve the issue. So please don’t think that we are grilling you, we just want to have all the information! We’ll be asking questions like, have you had any recent repairs, any other issues, how long has this been happening etc.

2. We’ll take it for a road test

Our trained technicians will pop out for a quick drive in your car to see if we can replicate the issue. This gives us a clearer idea of what you have been experiencing and gives us a good starting place to solve the issue.

3. Perform a fault code scan

This is where we start to get techy and where some people would suggest we are ‘just plugging it into a machine’. Please know that when you say that, every technician in the country rolls their eyes!

The best way to describe this step of the process would be to liken it to a trip to your doctor. You speak to the doctor about pain in your knee describing when it hurts and what seems to trigger it. The doctor will take a look but might not see any tell-tale signs. They then need to take you down for an x-ray, or maybe an MRI. Perhaps they’ll take some blood tests too. Each step the doctor takes is in a logical order, eliminating possibilities each time. This is how our technicians diagnose issues with your vehicle.

4. The visual inspection

Now that the diagnostic tools have shown us where the fault lies, we can get in there for a visual inspection of the components. If everything looks fine, we will continue to look for an answer.

5. Check the vehicle serial data

The car contains a control module which is like the brains of the car. We are able to review the data from the car brain for anything which might look out of the ordinary.

6. Technical service bulletins

Often called TSBs, these are updates direct from the manufacturer of any known faults.

7. Basic system checks

We are able to activate components within the car and test that all are working as they should.

8. The second road test

Sometimes we are able to diagnose the issue and fix it within one session. We’ll make sure the car is definitely running as it should be with a second road test before handing the keys back to you. This also ensures that we can spot any other issues.

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Are car diagnostics accurate?

Yes, as they are a direct response from your car’s computer system. It is up to the technician to then find the best repair to fix the issues you are facing.

What car diagnostic tools do we use?

At CCM we have a few diagnostic tools available to us including Autel, Bosch, Autologic, Snap-on and VAG-COM.

How often should you have a diagnostics test?

As we mentioned earlier, it’s worthwhile having a diagnostics test at least once a year on your car. This gives you the opportunity to spot any faults in their early stage, allowing you time to source a repair.

Trust our expert team

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