Stop Start Fault?

[thebig1]

Hi Guys,


Took my car C63s, to the dealer last week for a transmission software upgrade, door handle replaced and the stop start never seeming to activate, A on dash always yellow.
Picked up Thursday and told all fixed.
The stop start worked on the way home.


Today I drove 40 miles, all the temps where up, oils showing around the 80 degrees C etc, outside temp was 6.0 Degrees C but the stop start never worked, stayed yellow all the time.


I still think there is a fault?

 

[C36fan]

Hi Guys,

Took my car C63s, to the dealer last week for a transmission software upgrade, door handle replaced and the stop start never seeming to activate, A on dash always yellow.
Picked up Thursday and told all fixed.
The stop start worked on the way home.

Today I drove 40 miles, all the temps where up, oils showing around the 80 degrees C etc, outside temp was 6.0 Degrees C but the stop start never worked, stayed yellow all the time.

I still think there is a fault?

Maybe a fault with it but I would be glad if it happened to my cls as is very much annoying.

 

[Headhurts]

Start stop is very limited this time of year.

On mine it rarely comes on and then only works briefly.

TBH I am not too worried and mostly turn it off.

If it keeps doing this once the weather warms up then it may be worth another visit to dealership.


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[fordgt40]

I had the same problem, it turned out it was the main battery not holding full charge, dealer replaced it and bingo fault gone, but it does have a mind of it's own, sometimes works straight away after a cold start and other times stops working after a long run which I'm assuming is protecting the turbos, I've stopped bothering and run in sport mode all the time now.

 

[thebig1]

No idea how to get the dealer to change the battery. I would guess that by the time I drive to the dealership, they should be able to connect to the car straight away and know what issue is stopping it activating.

 

[AlexM]

Ditto - stop/start very rarely triggers in the depths of winter in my E63. It will usually work when the car has been standing for a while with a warm engine. I don't think there is a fault - it is just that all of the necesary conditions haven't been met. For example, is your windscreen clean? if it thinks the winscreen is misted stop/start won't work. The only time it actually didn't work was when the secondary battery faulted and needed to be replaced.

Cheers,
Alex

 

[thebig1]

Hi ya,

Had a list off MB today on what it looks for:

Vehicle stationary (It was, many times)
Outside temp in comfort range (It was 6 degrees and did work at 4 degrees so must be ok)
Engine at normal temp and sufficient fuel (Had driven 40 miles and over half full)
Set temperature inside reached (Again after 40 miles, 40 mins driving should be)
Battery sufficiently charged (Should be after 40 mins unless battery faulty)
The windscreen is not fogged up (How is this checked?)
The hood is close (Obviously was)
Drivers door is closed and seat belt is fastened (Obviously was)

So for me, either battery faulty or fault sencing windscreen fogged up?

 

[fordgt40]

I had to insist with the service people about the battery, there is only one on the C63, as they said there is nothing wrong with it, I have a certain knowledge and interest of how things work and have built and raced cars in the past, I monitored the battery voltage on my car, it never went above 11.7v engine off but 14.5 v engine running which suggested a duff cel not accepting charge, all this on a car 9 months old, they eventually gave in and replaced it.

 

[thebig1]

I am an ex auto electrician and now a principal electrical engineer designing these things so like you, has to be battery. Wish I could get the threshold battery measurements so I could put a multi meter on while driving and see the values


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[thebig1]

Just been informed by dealer that one of the active engine mounts is faulty and this might be causing the stop start issue. They are replacing it Monday