Do OBD mods leave a history of changes that dealers can access?

Tass

Active Member
Mar 8, 2020
18
6
A question: Do car's diagnostics only log fault codes, or do they log any mods made with tools such as OBD11 too?
I've had a scout through past posts and couldn't find a definitive answer on this...

My situation:
I have a car (2014 Seat Leon FR Hatchback) with gearbox issues. Following a botched clutch repair, the biting point is hazy and the clutch grabs unpredictably. Contributing to drivability issues is the fact that my car 'helps' with moving away from standstill, adding a blip of throttle (I think it's called an anti-stall feature?) exactly where I don't want one while I'm trying to match the revs to the biting point!

I would love to disable this feature so that I can get a clearer feel for the clutch issue alone (and also make the car more drivable while I continue to attempt to get the dealership to repair it). I understand from lots of past posts that it's easy to change this behavior using OBD11 and the 'direct throttle' mod. I am itching to get on and do it but I have one hesitation - will making the mod leave any form of entry in the car's onboard diagnostics that could notify the dealership that it was modified?

If it does, then I guess there's a chance that the dealer may use it as an excuse and say "You fiddled with it, hence you must have caused the issues, we're not taking responsibility". Obviously I realize the mod will change values deep within the coding, but my understanding is that this is unlikely to be noticed unless you went looking for it?

Any clarification on this, or advice gratefully received.
I'd love to make the mod and stop bunny-hopping across junctions. After 13 years of skillful driving, it really is mortifyingly embarrassing!
B-|
 

Legojon

I only wanted a remap
Staff member
Moderator
Jul 7, 2015
5,226
2,658
Well, from looking at what I believe is the "RAW" data in VCDs, it's just lengths of HEX codes. Sometimes about 32 characters for a system. I've also noticed across the 3 Leons I'd had ... and ok, they are different engines / trims, but the codes varied across them even for systems they had in common. All OBD11 will do is modify these hex codes. The dealer won't have anything to flag differences as the code will vary as well depending on what you change from the on screen display. So switching coming home lights on would change the HEX code for the lighting module. So again, from car to car, model to model and individual users settings, they'd never know. Worst case scenario, just set it back before you take it in. When dealers scan cars for faults, it doesn't show config information which is effectively what OBD11 is changing.
 
  • Like
Reactions: tak-fr

Tass

Active Member
Mar 8, 2020
18
6
Cheers Legojon
That's what I thought. That's really helpful to know (y)
 

Elliman98

Active Member
Aug 22, 2016
11
4
What Jon said, I work at a main dealer myself (not vag) and can only tell a car has been modified in that way when it’s been changed through the ecu (ie. a remap), rather than individual control modules as Jon explained, which is what you would be doing. I’d like to think it’s the same general consensus across all dealerships and brands but can’t be 100%.
Joe
 
  • Like
Reactions: Legojon

AndrewJB

Friend to SEAT UK & Cupra Racing
Aug 16, 2007
11,160
459
Maranello
If it was sent to Barca or even UK training centre they might be able to see changes but unlikely to get that far.
 

Legojon

I only wanted a remap
Staff member
Moderator
Jul 7, 2015
5,226
2,658
I think the point is... most of us know how time is money for mechanics. And if your guy is given 1 hour to service a vehicle or 30 mins to change a set of brake pads, he's unlikely to flag up or care that your indicators flash 5 times when the default is 3.
 
  • Like
Reactions: Tell

Tell

Full Member
Staff member
Moderator
That's how the mib2 navigation workaround passes by since the error code is difficult to clear. It's only if ODIS kept a library of what it was at the last service would they know.

VCDS is all a bit 80s computing but fun :). Kraftwerk ?. A little bit of German helps.
 
  • Like
Reactions: Legojon
AP Autostyling