Reading DTCs using generic OBD-II functions

[MarcelCh]

Hello to everyone. I am trying to read DTC codes using generic VCDS OBD-II functions on a faulty, non VW car. The connection works fine I am able to read data using mode 1. But when I try to read DTC (pending, or permanent) the response is "Not faults found". The system seems to use address 7e8 in the communication which seems correct.
However, when using different OBD-II dongle I get 2 different DTCs, P0335 and P0500.
Does anybody know why VCDS does not show any DTCs that are present? When accessing the OBD-II functions in VCDS, it asks to store the VIN which I deny beecause I do not want to code, clear codes or change anything. Could this be the problem?
Oh, and I am using VCDS 25.3.1. But do not suppose that generic OBD-II is updated among versions.

 

[Uwe]

I am trying to read DTC codes using generic VCDS OBD-II functions on a faulty, non VW car.

What car? What engine? What trans?

But when I try to read DTC (pending, or permanent) the response is "Not faults found".

There are three OBD-II modes for DTCs: Mode 3 (Current), Mode 7 (Pending), and Mode 10/0A (Permanent). Did you by chance you miss Current?

When accessing the OBD-II functions in VCDS, it asks to store the VIN which I deny beecause I do not want to code, clear codes or change anything.

No. That's a vestigial thing and has no effect on on generic OBD-II functionality.

Oh, and I am using VCDS 25.3.1. But do not suppose that generic OBD-II is updated among versions.

Generic OBD-II functionality does get updated from time to time, generally when the SAE/ISO specs for it get updated.

-Uwe-

 

[MarcelCh]

Thanks Uwe for your reply. It is a European Open(GM) Astra, 1.7 cdti (diesel) with a manual gearbox. Actually, I tried all modes except for mode 4 (clear DTC). In my case, modes 5&6 are greyed out. Is there any way how to enable debug mode and see the actual communication? Here and then I need to use a generic OBD-II.

 

[Mike@Gendan]

Thanks Uwe for your reply. It is a European Open(GM) Astra, 1.7 cdti (diesel) with a manual gearbox.

What year is the car?
EOBD only applies to diesel cars registered from 2004 onwards (2003 for newly-introduced models)

 

[Uwe]

Is there any way how to enable debug mode and see the actual communication? Here and then I need to use a generic OBD-II.

Sure. Go to [Options], set Debug Level to 1024, click [Apply] and then go to [OBD-II] in this car and do Modes 3, 7, and 10 to query for DTCs. This will generate a file ending in .DLM in your Debug sub-folder. You can e-mail that to Support@Ross-Tech.com along with a link to this thread.

Note that the Debug Level is not "Sticky", it will revert to 0 when you exit VCDS.

In my case, modes 5&6 are greyed out.

Almost certainly because your ECU doesn't support those modes.

-Uwe-

 

[MarcelCh]

What year is the car?
EOBD only applies to diesel cars registered from 2004 onwards (2003 for newly-introduced models)

Hey Mike, It is a 2007 Opel Astra H - as they mark it here in Europe.

 

[MarcelCh]

Sure. Go to [Options], set Debug Level to 1024, click [Apply] and then go to [OBD-II] in this car and do Modes 3, 7, and 10 to query for DTCs. This will generate a file ending in .DLM in your Debug sub-folder. You can e-mail that to Support@Ross-Tech.com along with a link to this thread.

Note that the Debug Level is not "Sticky", it will revert to 0 when you exit VCDS.


Almost certainly because your ECU doesn't support those modes.

-Uwe-

Thanks Uwe. I will do it once I get to that car and send it over.

 

[Andy]

We received your debug which shows you checked 07 and 10/0A but not 03 Current DTCs. Can you try again, selecting just Mode 3?

 

[MarcelCh]

I am pretty sure I have selected all functions but clear DTC. But I will do it again a resend it.

 

[Uwe]

I am pretty sure I have selected all functions but clear DTC. But I will do it again a resend it.

Please don't do "all functions but clear DTC" this time. Just do Mode 03. That will make the Debug file substantially less tedious to pick through.

-Uwe-