I tried the Carly car diagnostic tool and my life will never be the same again

As I waited for Dan from Carly to arrive for our scheduled rendezvous, my anticipation was building by the second. What if the scanner comes up with a million error messages? Will it be difficult to install the device? Would I, admittedly not a petrolhead, be able to use the dongle and the app? I had so many questions, especially since the concept of Carly sounded too good to be true.

The Carly app and its accompanying scanner allow car owners to perform vehicle diagnostics, view live data, and take advantage of expert guidance from their in-pocket Smart Mechanic feature, regardless of technical expertise. The scanner is a sleek and compact device that can be placed into the OBD (On-Board Diagnostic) port of a vehicle made after 2000.

Carly has been around for a while and is quite big on its home turf in Germany, but also in the US. In fact, I've been told that there are around two million Carly users worldwide, and despite the official UK launch happening right now, approximately 200,000 motorists are already using the device in the country. Most of these people are auto enthusiasts, of course.

Like most things in motoring, I expected Carly to be A) complicated to install and B) not easy to understand. I imagined having to pop open the bonnet to connect the scanner, going through a cumbersome 'what does this cable do' and 'why isn't it connecting' process. Instead, all I had to do was get Carly out of its box – it's like an oversized USB stick – and plug it in the OBD port on the right from the pedals.

Super simple stuff. Once installed, I put on the ignition and opened the Carly app on my phone. Running a diagnostic on the car is as easy as tapping on an icon in the app, and after a few seconds, voila! The results are in. Dan from Carly, who very kindly supervised the process, said not to get too scared once the initial diagnostic data comes in.

Often, garages don't clear error messages even though they fixed the issue, so Carly may pick up a bunch of error codes left in the system. It can be scary to see any error codes, let alone 20, especially if they say, 'YOU NEED TO GO TO THE NEAREST GARAGE ASAP!' Thankfully, my initial report returned with only two error codes, and neither was of the 'severe' variety.

The diagnostic feature alone would be enough to convince me to try Carly, but this is just the tip of the iceberg. That said, even just knowing the codes can give some of the more anxious of us peace of mind. If you think about it, we put all our faith in garages telling us what's wrong with our cars, which is a bit of a lopsided relationship. Carly can help balance this by telling you what people in the garage see when diagnosing your vehicle.

But the Carly ecosystem goes beyond merely offering you a list of codes. Once Carly locates an error, you enter Smart Mechanic mode, where you can further scrutinise the issue. Smart Mechanic provides an explanation of what the error code means, what the symptoms are, possible causes and how to investigate it, should you want to.

Better still, it breaks down the main error code into sub-codes, all of which you can further scrutinise. Plus, Smart Mechanic also helps understand the context of the issue by offering more in-depth explainers of the car parts and links to relevant content about the issue online.

But wait, there is more! The Intelligence feature within Smart Mechanic looks at the error, checks the history of similar errors in similar vehicles to yours and can predict upcoming errors based on Carly's database. It's like Minority Report; the faults might not happen, but there is a good chance they might. And now you know how to react to them.

I can almost sense you saying, "Matt, it's so much already!" You're right. However, this is just one of many features of Carly. You can also set reminders for specific service issues in the app (e.g. oil change, brake fluid, etc.), read live engine data (admittedly, it's a bit more techy), and run a used car mileage check.

Used car mileage check is done the same way as your standard diagnostic: you pop the scanner in the OBD port and let Carly do its magic. In the report, you can see if the car's data has been tampered with, including if there's a difference between mileage shown on the speedo, what data is stored in the engine's memory, and more.

And yes, there are yet more features! You can run a battery check using the scanner. First, initiate the feature using the Carly app, then use the car normally for 24 hours. Once the period is up, open the battery feature, and it'll give you a rundown of the battery's health status. Mine came back saying the self-discharge was 7.4%, which is not great (it might need replacing).

Considering how much data Carly provides and the savings you can achieve by fixing smaller issues in your vehicle yourself, you might think it costs thousands of pounds. It doesn't. You can buy the Scanner only for £74.80, which gives access to full OBD features, including OBD level diagnostics, OBD level parameters, and the emissions check.

Admittedly, this isn't much more advanced than your no-name OBD reader you can buy at Amazon, but at least it's only a one-off cost – no strings attached. Things get more exciting when you start adding features. The Premium Package for a single brand (e.g. BMW) starts from £56 a year. Not a month, not per diagnostic; an entire year. This includes the Scanner and all available features excluding Smart Mechanic.

That's another £35.99 per annum, but it unlocks all features of Calry, which is what you need, really. Finally, for another £20.84, you can upgrade your premium subscription with access to all vehicle brands. You can run diagnostics on all the cars in the family, all the time, for this price.

Okay, let's do the math. Let's assume you went with the more expensive package: a £74.80 one-off cost and £112.83 annually. That's £9.40 a month for something that can literally save thousands down the line. The Standard package on Netflix costs £10.99 a month, which won't save you any money, ever. Crazy.

If I were you, I would at least entertain the idea of checking out Carly. It's so simple to use, yet it has gazillions of benefits. If you're interested, head over to Carly today, and experience the magic yourself.