The infamous ELM327 OBDII device came without any paper, just a crappy CD with no document related to the device (only some software and drivers thrown on the CD almost randomly).

I tried the following codes without being able to pair it with my HTC Desire HD:

  • 0000, ..., 9999
  • 1234, 2345, 3456, 4567, 5678, 6789, 7890

What other PINs should I try?

  • so, which one was it? 1234 or 0000 or 1111 or maybe 6789?
    – user2747
    Commented Feb 11, 2013 at 18:40
  • My code was 6789 for standard ELM327 OBD 2 chinese bought on EBay.
    – user2839
    Commented Mar 6, 2013 at 2:01
  • none of the above worked for me, still searching
    – user2859
    Commented Mar 9, 2013 at 22:29
  • 2
    It seems that the correct code was already one of the listed ones, still there is a trick: it seems you are able to put the PIN code only one minute after the device was powered. Unplug it and try again, preferably with a computer. Don't try iPhone as it will not work.
    – sorin
    Commented Mar 11, 2013 at 9:44
  • I bought a iKKEGOL Bluetooth OBD2 OBDII Scanner and didn't know the code. I did a google search and found your question. The passcode for the ikkegol scanner is "1234". Cheers!
    – radtek
    Commented Nov 18, 2016 at 18:08

3 Answers 3


Is it the one pictured at the Elm327 Bluetooth website?

If so then the passcode should be 1234 although technically they say that the passcode is

" 1234 "

It's been a while since I paired a bluetooth device but I think you only get 4 digits to work with, not 6, and I think only numerics are allowed so no spaces either, which brings us back to "1234"... which you've already tried.
Have a read over the website above and check out the Bluetooth User Manual page, the instructions don't exactly match connecting to a phone like you are trying to do, but maybe they'll give a clue to a step you might have missed or something.
Sorry I couldn't be of more help.

  • I tried 1234 with the Phone but I repeat the process with a computer, maybe there is an issue with HTC.
    – sorin
    Commented Nov 16, 2011 at 3:47
  • Numbers 1234 worked for me, pairing with a MacBook. Won't work with iPhone or iPad since iOS only accepts Bluetooth LE (Low Energy) devices, which are still quite rare. Mind that my MacBook now sees the adaptor, but OBD Auto Doctor does not. Trying out different software ...
    – Eloy
    Commented Apr 3, 2016 at 17:51
  • 1
    While 1234 worked for me, the finding about the need to pair soon after the activation of the device actually helped me most.
    – palswim
    Commented Dec 10, 2016 at 6:44
  • 1234 but had to retry several times with the phone (did not restart between attempts so it wasn't time based). Also had to refresh the Bluetooth search several times to get it to show up originally. It seems like whatever bt chipset is going in phones for the past few years has trouble pairing to these old devices, so failure doesn't always mean a wrong code. Commented Dec 25, 2020 at 20:51

The PIN code is 6789 (instead of 0000 or 1234).

  • that worked for me
    – Jonny Lin
    Commented Mar 15, 2016 at 1:43

It seems that the correct code was already one of the listed ones, still there is a trick: it seems you are able to put the PIN code only one minute after the device was powered.

  • I'm confused. Does this statement mean "only for the first minute" or "only after one minute"? I guess "only for the first minute" makes the most sense, but undocumented behavior doesn't have to make sense.
    – Guy Gordon
    Commented Mar 22, 2018 at 14:17
  • 1
    @Guy, if it doesn't pair and the device has been powered for more than a minute, turn the car all the way off then turn it back on to "reboot" the OBDII device, and try pairing it again. I experienced this today where repeated attempts at pairing failed until the car was turned off and back on again.
    – kbulgrien
    Commented Dec 12, 2018 at 5:11

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