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I have been extracting OBD-II DATA from UART board (ELM327) on my TOYOTA INNOVA. It responded correctly few weeks before and gave all supported sensor values. But now, for every response, ECU responds "7F 01 11". Please tell me what exactly this output means and how to get rid of this problem

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It means the requested PID is not known – Juann Strauss May 29 '14 at 12:42
@JuannStrauss lets take 010C, a standard PID. Why is that when we tried before, the car responded correctly but now not responding . How can we get it fixed? IS that because of some changes in ELM327 (UART Board) – user3098378 May 29 '14 at 13:30
I can't say without seeing your code, but it may be that your header has changed or you're requesting the wrong mode. Or maybe you changed the baud rate. – Juann Strauss May 29 '14 at 18:44
@JuannStrauss I did change the Headers through ATSH XXX when i was monitoring CAN DATA through ATMA. Then i did reset it many times through ATZ and ATD, is there any other way to reset ELM to original state like with Headers off or reset. – user3098378 May 30 '14 at 7:00
@JuannStrauss : Could you compile the comments to this question as a generic answer for containing possible reasons? I want to move this question out of the "Unanswered" territory – Zaid Dec 13 '15 at 19:42

7F = general fail response.

11 = Service Not Supported.

That is the meaning. It's odd that it was working before. Ultimately, it could be the device that you are using to read the codes is defective.

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