C5A: Disable Start&Stop permanently (maintenance mode?)

[zakazak]

Hi again

I bought my C5A used from a dealer 6 months ago (12.2019 with 30.000km). Since then the Start&Stop never kicked in even once. It would always show the A sign, it blinks 3 seconds, then disappears.

Today while applying Anti-Rust fluid I disconnected the battery and since then Start&Stop suddenly works as intended.

I wonder if it was deactivated through some kind of maintenance mode or a special mode that car dealers can set? I remember that when I went for a test drive, the dealer said that he just has let the engine idle for several minutes so that I wouldn't test drive with a cold engine. The engine was running when I got in the car, the "disable Start&Stop" button was pressed.

[GiveMeABreak]

You can only disable the system temporarily at the beginning of a journey after the engine has started. It will stay disabled until the engine is restarted. It can't be turned off permanently - but in most cases, it is disabled as in it hardly ever works of the battery is not at 80%+, plus all the other factors required for operation.

[zakazak]

You can only disable the system temporarily at the beginning of a journey after the engine has started. It will stay disabled until the engine is restarted. It can't be turned off permanently - but in most cases, it is disabled as in it hardly ever works of the battery is not at 80%+, plus all the other factors required for operation.

This is what I read everywhere but it can't be.

6 months and not a single Start-Stop engaging?
Today with an relatively empty battery and cold weather conditions I get Start-Stop on every stop?

That is no coincidence :S

Edit:
According to users on reddit there is an option in diagbox that does disable it exactly until battery disconnect/connect. I don't have diagbox ATM to check it though.

[Paul-R]

How exactly do these Reddit pundits say to disable the S&S? Where is this option?

Or are they just repeating what others have said without evidence?

[zakazak]

How exactly do these Reddit pundits say to disable the S&S? Where is this option?

Or are they just repeating what others have said without evidence?

I found two guys explicitly saying that there is an option and PMed them for more Infos.

In a German Forum a guy posted screenshots where you can change the type of battery in diagbox (AGM for Start-Stop or smth else) but that didn't effect Start-Stop. He later posted that he found an option to disable Start-Stop as well as setting the status of the "disable start-Stop button" but didn't add any further Infos.

I will try calling my dealer on Monday. I am 100% sure it was deactivated until I disconnected/connected the battery. Which also exactly what the people on reddit noted.

[zakazak]

One reply I got:

under maintenance, there should be a separate system (like ECU) - "start stop system" or something like that.

[GiveMeABreak]

I can only give you the multiple reasons for the system not to work - all these have to be met for it to activate. I'm only aware of the temporary disablement via the button. I certainly wouldn't be messing about with internet dudes who probably have no clue what the consequences of changing settings may have on their vehicles. Not everything means what it appears to be regarding BSI configuration. I've certainly had my share of helping those that bricked their vehicles as a result of following internet videos....

[zakazak]

I agree with you about following random internet heroes suggestions in tools that are made for professionals who get training for it.
In my case I am very certain that the dealer deactivated it though.

One thing I noticed this morning:
The Stop-Start engages even on a cold engine.
I left the garage (12 Celsius Degree ambient temperature) and the Stop-Start engaged on the first stop (about 20 seconds after starting the car).
It kept engaging with every stop. Here is a picture where the engine oil temp is still on "0" wheres the coolant is at "20%".
Link: https://files.bestmail.ws/C5A/photo_202 ... -14-17.jpg

This shouldn't happen? Stop-Start should only work when the engine has normal driving temperatures?
So I am wondering if a cable is connected to the battery which might be disconnected now as well?
Because I also read about tricks online where people would disconnect a cable that is attached to the battery and would tell stop-start systems the current charging status or ambient temperature.

[wheeler]

Cant think i have ever seen a setting in Diag box to turn it off. I know you can get the ECU remapped to make it default to off.

[zakazak]

Search for ECU EDC17C60 (might be different based on model). Then go to:

-PACK REPAIR
-SERVICE ACTION
-WORK ON THE STOP AND START SYSTEM
-ACTIVATION OF THE STOP AND START
-INHIBITING OF STOPPING

How every I might actually be happy with stop start but I just don't understand why it turn if the engine when the ambient temperature and the engine is cold? Isn't that especially bad for the engine?