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I bought JDiag Fastlink OBD II scanner which is based on ELM327 based OBD II scanners. I noticed that the scanner was able to read all the instrument panel reading such as fuel level, engine temperature, RPM etc. but somehow the scanner doent read any trouble codes, eventhough the car has check engine light on!

I am curious to know if the fault codes from the ECU are encripted such that only advance scanners can read them? Or this functionality is purposely suppressed in cheap scanners? Since the scanner could read all the guages in the instrument panel then why cant it read the fault codes? Or maybe for each car the fault code had to be added to the software for OBD scanner to detect it?

I tried on Mini Cooper 2011 as well as Jeep Wrangler 2012 which obviously had faults but the scanner returned no codes!

  • If you have an ELM327 based OBDII scanner, you might try using a different program to run it, such as "Torque (Lite)" (for Android devices). It is a free app and can be retrieved from the Play Store. – Pᴀᴜʟsᴛᴇʀ2 Sep 1 at 15:29
  • @Pᴀᴜʟsᴛᴇʀ2 alright, Ill did hear about it and will give it a try. But I am quite curious why the stock software (which is supposed to be well adapted with the hardware it comes with fails to show codes) the conclusion I get is maybe each car comes with its own database of codes or something that the software might not have or something of this sort. – gfdsal Sep 1 at 15:35
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No, the codes are not encrypted. They do have a protocol which is used to decipher them, though. For instance, Honda uses the J2284 protocol and GM uses the J1850. There are a few others out there as well. Since you are able to see engine diagnostics, your reader is utilizing the correct protocol and has that ability.

My thinking on your issue is, you might not be looking in the right place to find the codes. The purpose of an ELM327 interface is to provide a wireless interface through the CANBus, and then to read and reset engine diagnostics. If the software you're using does not have the ability to clear or show you the codes, you should be able to use other software to do what you need to do.

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  • Alright, this makes sense. you might not be looking in the right place to find the codes actually I did the procedure correctly, there is a button that says scan but after scanning it simply shows no-faults. So that begs the question could it be data base thing? since as you mentioned that the protocol is there that is why I can read guages but the fault codes arnt showing. – gfdsal Sep 1 at 18:46

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