I got myself such a bluetooth adapter for my car, because the display on the radio stopped working, and I wanted to see if it will show up any errors. There are even apps for Android that work with said bluetooth adapter.

My question is, are the Android apps reliable, meaning, would they show as much data as a PC software would show when connected to the bluetooth adapter?

Also is this adapter good for all kinds of diagnostics regarding the car? What are the differences between that one, and the more expensive ones with cable for diagnostic (I've seen some for more than 100$, and the bluetooth one I got is just like 13$)?

  • I'm still wondering how an OBD-II reader is going to show you anything to do with your stereo ... ?? Jan 20, 2016 at 15:35
  • I am not a car technician, how should I know Jan 20, 2016 at 18:59
  • I'd just hate to see you waste your money buying something which isn't going to get you what you need. Asking the right questions is going to get you on the right track. Jan 20, 2016 at 19:40

2 Answers 2

  • The ELM327 is (almost?) as powerful as any other diagnostics solution. That's simply because it only translates the low level OBD protocols to some other format.

  • Bluetooth connections on mobile phones seem to be flaky on many devices. Usually, this shows as established connections suddenly failing during transfer. Restarting the app, and/or turning the phone's BT off and on may be required, or even a full reboot in some cases, to get BT back working.

  • What you can or cannot do with the ELM fully depends on the software you use. There is a host of apps and other SW which support only the most generic standard OBD PIDs, of which "Torque" is the most well-kown. This may or may not be enough for your case.

  • Any fault detected by one of the ECUs should be readable by any standard software. However, there are standard and non-standard fault codes, and generic software will often only display the numerical fault code for make/model specific faults and not the full textual description and/or hints on how to fix the problem.

  • For some makes there are specific apps available, like "Carly for BMW" for instance, which know how to query and interpret make/model specific, non-standard data.

  • A full PC software suite, especially professional ones used by garages or dealerships similar to e.g. VCDS/VAGcom, will provide more features, like configuring or updating ECUs' firmware, which most apps don't yet.

  • Generally, bluetooth or cable does not make any difference when it comes to functionality. It's rather a question of what the software supports; AFAIK, VCDS is dongled to their own proprietary diagnostic hardware for example.


Just get one of those $10 BT-ELMs and check if it does all you need with some (free) apps, which I think it will. Reading and clearing fault codes will work.

If you find you have a real need for more features you'll have to locate a capable software and check what kind of adapter that specific software requires.

  • I sometimes use ELM327 myself with a Volvo and any software I try says there are no DTCs, even when that is not true. Not even a Volvo specific unidentified code, nothing. That's why I am forced to use another tool only for the codes. Only good the the PIDs, really. Jan 20, 2016 at 14:22
  • Interesting. Some quick googling suggests that Volvo may have been using non-standard physical pinout on its OBD connectors, so that some ECUs are not accessible via the standard data pins.
    – JimmyB
    Jan 20, 2016 at 15:50
  • Well, the car I'm talking about conforms to ISO 9141-2 standard. Reading PIDs works well, but some DTCs get left out (and some are shown). Jan 20, 2016 at 16:59

Bluetooth ELM327 adapters are horrible, I found the Bluetooth connection to be extremely unreliable. Spend some extra and get the USB version, if ELM327 is what you want. The Android apps have the potential to show the same information as the PC applications, but usually the features on the Android apps are limited, it depends on the applications themselves. However the data you can get may be not much either way, as the ELM327 is a universal chip - it will only get you the most common generic codes for some of the cars.

I don't recommend ELM327 for reading codes at all, unless you have an Engine Check Light on and need something to get you on the track. I am quite certain that even if there is a code for your radio display (unlikely), ELM327 wouldn't read it. For that you need vehicle specific reader, as some codes can be only read by those. It is not necessarily expensive, there are cheap OBD cables for many makes. What car do you drive?

I find ELM327 to be alright for reading sensor data, though.

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    I agree with that. The cheap bluetooth adapters are extremely unreliable (I have serveral of them), the more expensive ones (I have one for ~100€) work well though. Jan 20, 2016 at 14:32
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    I have one of this blue transparent dongles. Pairing mobile and dongle takes lots of time, and it seems the dongle is only "willing to pair" right after power on. And when I start the motor, the pairing is lost and needs to be established again. Also, pairing seems to be strange. I have to remove the device from the list in the mobile and let the app find it again... Internet research shows that there are lots of exact clones out there, which don't work properly. It seems to be difficult to get genuine ones, which promise to work better, but also cost more!
    – sweber
    Jan 20, 2016 at 14:43
  • @user5626466 Yes, I was talking about the super cheap scanners Sartheris mentioned. Is your scanner also based on ELM327? What do you use it for? Jan 20, 2016 at 14:48
  • My scanner is also based on the ELM327 chip. I use it to look at realtime data and to read and erase error codes using torque on android. Jan 20, 2016 at 14:55
  • Quite a pricey solution. I found the cheap USB based scanners to reliable as well. Problem is that you can't connect it to a dash mounted tablet for live sensor data feed. Which would be awesome. Jan 20, 2016 at 15:04

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