The best car diagnostic tools

These little devices will help you identify tricky faults in modern cars.

best car diagnostic tools

by Chris Williams |

A diagnostic tool is self-explanatory in its function – identifying car gremlins. However, before we go through the best ones, let’s answer an important question:

What's the point of a car diagnostic tool?

Having a device that tells us what problems a car has is great, but if we aren’t mechanics who can act on the identified faults, surely it’s a bit pointless? Like a home-use Hubble Space Telescope diagnostic tool.

Not quite true.

Granted, basic car fettling is not what it used to be before hi-tech electronics made their way into mainstream cars. However, that itself is exactly why car diagnostic tools are useful these days. Ever-more frequently do we take our cars to be serviced and have to fork out large amounts of money for faults that we don’t understand or have explained to us. With a diagnostic tool, we can send our cars to be serviced with a much better idea of what the fault is. Use the information to undertake some internet research to make yourself informed about the issue, then take your car in to be serviced. In doing this, there's the potential to save yourself a considerable amount of money in servicing costs.

It's easy to give manufacturers and mechanics the benefit of the doubt with sorting your modern car’s faults without sliding in extra or unnecessary costs. However, diagnostic tools connect to a car’s OBD II port, which is quite often hidden in the car somewhere obscure. One could argue this is meant as a slight deterrent for people wishing to run car diagnostics at home.

There is a difference between readers and scanners

The most obvious difference between code readers and scan tools for cars is the price. Scanners are more expensive on the basis that they do more. Readers can essentially identify generic issues, whereas scanners are able to also read vehicle or manufacturer-specific codes.

We recommend readers for those who wish to understand a bit more about car troubleshooting and scanners for the more serious home mechanics and DIYers.

How do diagnostic tools work?

Fairly straightforward: turn your car off, and once you have located your car’s OBD II port (this may take some research), plug the diagnostic tool in. OBD II ports are often found beneath the steering column.

Turn the ignition to whichever setting the tool suggests. Your scanner or reader will then either power up automatically, or you’ll need to turn it on. Then follow the prompts and enter the required information - usually basic car details.

From there, you will be able to use the diagnostic tool to read trouble codes.

Obviously, individual tools will have certain limitations, and as mentioned, readers will only give you basic information – a trouble code it may identify could have various causes. This is where scanners step in.

Below are our pick of the best car diagnostic tools. Remember that you should check your car’s compatibility with any of them first.

Read next:

Best car battery chargers

Best car tool kits for those DIYers

The best degreaser for cleaning engines and bodywork

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