Scary Stop-Start malfunction

[DaveSumnerSmith]

We are having problems with the Stop Start that are becoming increasingly frequent - and dangerous!

In the last three months there have been four occasions when either my wife or I have been through the following sequence of events:

1/ Pull up at the stop line to enter a roundabout (we live near Milton Keynes, so there are lots of them!)

2/ After a few seconds the 2.0TD engine cuts out (as it should) to save fuel

3/ Take foot off brake. Engine restarts.

4/ Press accelerator & move out onto roundabout.

5/ After 5-10 yards the engine dies & the vehicle comes to a halt.

6/ Put auto gearbox back into neutral & restart (as quickly as possible) waving apologies to other motorists!

It is only a matter of time before this causes an accident. We have taken to disengaging the Stop-Start completely. But this should not happen.

At this moment we are driving an A4 Avant courtesy car, having refused to take the fully serviced Q5 back after a service until / unless the Audi dealer sorts it out.
The fact they cannot find it on their analyser is neither here not there. Nor is the fact they have driven to a few roundabouts and been unable to replicate this dangerous problem. 

[Brad-B5]

Hi David

That is pretty scary and very dangerous as you said, I don't know what is going wrong but I'm sure someone on here will know and keep us updated!

Regards

Bradley

[Magnet]

Hello David,

I certainly don't want to claim any expertise with this, but perhaps some logical thought might point to the fact that the engine cuts out when it needs to when the brake is applied when stationary. Now, if it cuts out when it should not, then is this issue linked to some fault within a brake switch? Of course, this arguement may be knocked on the head by some logic that the engine cut out (when it should) is actioned via. a combination of brake switch and a sensor which senses the car is stationary. 

Not sure whether this is of any help or not - I guess not. 

I am not going to wish you good luck in getting this sorted - it should not depend on luck!

Kind regards,

Gareth.

[Trevor]

Hi David

I do wonder if Magnet is right, something that signals the stop/start to function but not show on the scan....maybe something as simple as a brake light switch.

Either way, I think you are right not to accept the car back from Audi until this potentially dangerous fault is rectified.

Keep us updated on the progress as would love to know what's causing it

Cheers  Trevor

[Envy]

Hi Dave, 

Similar fault on A6 C7 Forum... 

No news on her resolution from her either. 

Has to be Software or Sensor (does not leave a lot otherwise). Lots of complex algorithms running on dependencies. 

Hopefully Audi can get to the bottom of things.