Carly — OBD2 car scanner

Review by eFreeware

A warning light comes on, and the choice is usually between ignoring it and paying a shop to read the code. For a lot of drivers, the second option is the only one available, because the equipment that talks to a car's computers has traditionally belonged to workshops. Carly is an attempt to move that capability onto a phone, and it comes from Carly Solutions GmbH & Co KG.

The app is free to install and carries no ads, though it does offer in-app purchases. It has been on Google Play since October 2012 and has passed a million installs, with a 3.7 average across more than 34,000 ratings. Those numbers suggest a tool with a real following and a fair share of frustrated users, which is worth keeping in mind before you spend anything.

The app is one half of a system: it reads data that a physical scanner pulls from your car's OBD2 port, so the two are meant to be used together. That distinction shapes everything about whether it makes sense for you.

What the scanner and app do together

The pairing works in three steps. You check whether your particular car is covered, order the Carly Universal Scanner, then plug that device into the OBD2 port and sign in to the app. The scanner is the hardware half of the product, and the developer backs it with a lifetime warranty and premium customer support.

The hardware is built to work with almost any brand that has an OBD2 port. Supported makes include Audi, BMW, Ford, Lexus, Mercedes, Mini, Opel, Porsche, Renault, Seat, Skoda, Toyota and Volkswagen. That is marketing language, but the breadth of the list is the practical point: this is not a single-marque tool.

One caveat the developer is upfront about is that every car is different. What you can actually do varies with the car's model, year and hardware. That is normal for this category of tool, and it means the sensible first move is checking your own car before ordering anything.

Diagnostics, codes and live engine data

The free basic package covers three things: OBD diagnostics, live data and an emission check. Together these give you a view of the engine and transmission, which are the systems most likely to trigger a dashboard warning. For a driver who simply wants to know why a light is on, that is the core of the app.

The premium package, sold as a yearly license, goes deeper. It can pull and reset fault codes from every onboard control unit, not only engine and gearbox. The developer lists engine, transmission, ABS, airbag and multimedia among the units covered. It also promises help gauging how severe a problem is, which matters when you are deciding whether to drive on or stop.

Live data is the other half of that picture. Watching parameters as the car runs is how you narrow down a fault that only appears under certain conditions, and it takes some of the guesswork out of deciding what a car actually needs. I would expect this to appeal most to someone who already has a rough idea of how engines behave, because the raw numbers only help if you can read them.

Repair guides, servicing and battery checks

Beyond fault codes, Carly bundles a set of maintenance tools. Repair guides are matched to the specific issue the app has identified, with the aim of helping you fix it yourself rather than hand the car over. The maintenance feature walks through servicing step by step, resets service reminders and keeps track of your service intervals from the phone.

There is also a battery check that monitors the state of the starter battery, which the developer links to getting more life out of it. A failing battery causes a surprising range of misleading symptoms, so having that reading in the same place as everything else is a sensible arrangement.

Coding is the feature that will interest tinkerers most. It lets you reach hidden functions the manufacturer left switched off and adjust the car to your preferences. The developer is clear that this only works on certain brands and models, and that the options differ from one control unit to the next, so it is not something to buy the app for on faith.

Checking a used car before you buy it

One use case stands slightly apart from ownership: inspecting a used car before purchase. Carly can check for mileage manipulation, which the developer notes is on the rise. A seller who has wound back the odometer is hard to catch by eye, and a tool that reads what the car's own electronics recorded is a reasonable line of defense.

For anyone shopping for a secondhand car, this turns the app into something you use a handful of times rather than daily. That is a different value calculation from the owner who wants to service their own vehicle, and it is worth being honest with yourself about which camp you fall into before subscribing.

What Carly asks of you

The app is free to install. You need the Carly Universal Scanner, which is a separate purchase, and the advanced features sit behind a yearly license. The subscription can be bought for a single car brand or for all brands, and it renews automatically for another year unless you cancel at least 24 hours before the current period ends. Cancelation is handled through your purchases.

That structure means the real cost of Carly is the scanner plus a recurring license, not the download. If you own one car and plan to keep it, the single-brand option is the narrower commitment; the all-brands license only makes sense if you expect to work on several vehicles.

There is also a learning curve. Reading live data, interpreting fault codes and using coding functions all assume some familiarity with how a car's electronics are organized. The app supplies guides, but the underlying knowledge is yours to bring.

Getting the most from it

The single most useful habit is checking compatibility before you buy anything. Because feature availability shifts with model, build year and software, confirming what your car supports is the difference between a tool that earns its keep and one that sits unused. Do that first, then decide on hardware and license.

Once set up, I would treat the app as a record keeper as much as a diagnostic tool. Tracking service intervals and battery condition over time is where a phone-based system has an advantage over a one-off visit to a shop, since the history stays with you rather than in someone else's filing cabinet.

For fault codes, the sensible sequence is to read the code, look at the severity guidance and the matching repair guide, then decide whether the job is within your ability. Carly is at its best when it informs that decision rather than replacing a mechanic outright. Coding is the one area I would approach slowly, changing one thing at a time so you can tell what caused any difference in behavior.

A capable tool for hands-on owners

Carly is a serious piece of kit wrapped in an app. It reads and clears fault codes across the major control units, shows live engine data, guides repairs and servicing, monitors the battery, opens up manufacturer-hidden settings on supported cars and can flag odometer tampering on a used vehicle. The free tier covers the basics; the yearly license and the scanner are what unlock the rest.

It suits owners of out-of-warranty cars who are comfortable getting their hands dirty and want to know what is wrong before agreeing to a repair bill. It also suits anyone buying a used car who wants a second opinion on the mileage. The 3.7 rating from a large pool of reviewers suggests the experience is not uniformly smooth, and the brand-by-brand differences in feature support mean your results will depend heavily on what you drive.

If you want a diagnostic tool for a specific car you intend to keep, and you are willing to buy the scanner and pay for a license, Carly is a well-established option with a broad brand list behind it. If you would rather not own hardware or commit to a yearly subscription, that is a different setup.

What's new in version 50.02

- All Carly brands in ONE app