Car Scanner App ELM: Best Free OBD2 app?

Even after a few years, in 2025 it is still the best free OBD-II app you can pair with the ELM327 adapter.

I tested a lot of different apps, but from all the generic car diagnostic apps I tested, the car scanner offers access to most data, and most features and it is easiest to use without too many annoying ads.

What is the Car Scanner ELM OBD app?

Car Scanner ELM OBD2 is a top-rated free OBD2 app for iOS and Android operating systems. It stands out by being able to do a full scan, not just the engine, like the other free OBD2 apps. Displaying multiple live data graphs and ECU coding is also unusual in this price range. You can even extend the functionality by purchasing a cheap pro lifetime license for only $5.

What vehicles work with Car Scanner ELM 327?

I couldn’t find any lists of supported vehicles, but I assume that diagnostic features like scan and live data will work for all OBD2 vehicles. I never had problems connecting to a car and tried many different car brands. I tried it on Toyota Corolla 2022, VW Jetta 2016, and Audi A8 2013. It worked fine for all models.

What can you do with Car Scanner ELM 327?

This car scanner app is your best bet as your first car diagnostic tool. While it doesn’t have every function that professional scan tools have, it provides enough functionality to be helpful for car owners and DIY mechanics. It will read codes and live data; it is only up to you to gain the knowledge to understand what these data are trying to tell you and use it for your problem diagnosing.

1. Do a full scan

Read OBD2 trouble codes and erase them if needed. The app can read DTCs (OBD2 codes) from your car’s engine control unit and all other control units. Diagnostic tools in this price range can usually only read trouble codes from the engine, but the Car Scanner app can read codes from all control units. A modern car can have up to 50 control units, some even more, so Owning a device that can scan all of them is helpful.

2. Display engine live data

You can read live data from the Engine control unit and display more of them in one graph or add up to 4 different live data graphs on your screen. I even used the mirror link function on my phone to transfer this data from the smartphone to the car’s radio. Not all cars will be able to do this. I also have a starting guide to understanding live engine data.

3. Show freeze frame for trouble codes

You can see the freeze frame data, which are live data values saved from when the trouble code was stored in the ECU. Every trouble code has its own freeze frame data, and they can be helpful to look at when you are trying to figure out the conditions in which the malfunctions are happening and what is causing them.

4. Noncontinious monitors

Display live data values from sensors and add maximum and minimum values. The DTC is set if the value gets higher or lower than expected. You can see the minimum and maximum allowed values for all sensors. It will help you understand your vehicle’s right live data values for multiple engine sensors.

5. Readiness

Readiness on a scan tool is an OBD2 check of components of your exhaust and emission control systems. Each component will be marked as “OK” or “Faulty” based on their conditions. Readiness is the basic function of almost all OBD apps and classic code readers. You can use it to check the vehicle before state emission inspection if you are in an area where it’s mandatory.

6. ECU coding

This is another function that sets Car Scanner App apart from the competition. This is the interesting part. The ECU coding function is almost Sci-fi in the OBD2 tool in this price range. I tried it, and it worked great. You can also use the Carista app with the same adapter for additional coding and service options. For example, I could enable window control from the key fob on Toyota Corolla.

7. Display live data gauges

You can build your custom gauge page by choosing which data will be displayed and how many of them and choosing the display form. It doesn’t have to be a gauge; it can be displayed as a bar or text value. There is even a button to mirror your phone’s screen to use your phone as a head-up display.