Stop / Start Fault?

[slipped_disc]

My wife has a manual 1.2TFSI A1 Sport. The stop / start system is stopping the car as it should, but every time the car should restart it displays a message saying that the car must be started manually with the key.

The handbook does make reference to this but does not say under what conditions the car will not restart. She isn't doing anything like opening the door or unbuckling her seatbelt, etc.

The car is currently with Audi, who have checked the battery, changed an earth cable and are now in email correspondence with Audi HQ regarding the next step. The local dealer isn't giving us much confidence of a quick fix.

I was wondering - has anyone else experienced this and had it successfully repaired? I've seen a few mentions of the problem on the internet but none with much detail of the repair.

 

[josedebardi]

I've heard of this, but unfortunately there are MANY reasons for it!

Off the top of my head, here are a few to try...
Battery is too low

Alternator is faulty

Key battery is low (if it's advanced key)

Some sensor is reporting something off (should be easily read by Audi or a 3rd party with VCDS)

She is selecting 1st gear with the engine off and clutch up, then dipping the clutch (long shot but I know it produces the message you mention)

 

[slipped_disc]

Thanks for your reply but I'm not so sure it's any of those. What I don't understand is, why does the car let the engine stop in the first place, then decide that something's wrong that won't let it restart automatically?

I'd have thought that the first thing Audi would have checked was the diagnostics if there was a faulty sensor.

It is doing it every time, so it's not that she's putting it into gear by mistake (which I can understand would cause the error)

My wife's logic is: Audi designed and built the car - surely they should know why it doesn't want to restart!

 

[josedebardi]

I would expect there to be an obvious error once they hook it up to a computer as well.
It may let the car stop because when the engine is running the voltage on the battery looks good (thanks to the alternator), but once it stops something goes awry. The question is what is the something!

Where are you based/what dealership are you using? If there is another local one it may be worth getting a second opinion from them.

 

[josedebardi]

It could be the clutch position switch or the gear position switch. If either of these are faulty it would not necessarily show up a fault.
Does the car show the correct gear on the dash when you are driving around for every gear?

 

[slipped_disc]

I'm in Northern Ireland, so I'm not blessed with much choice of dealership. The current dealer seems to be taking their advice from Audi HQ before trying anything, so I'm not sure any other dealer would be different. I think they don't want to try anything or order parts when there's a risk that they won't be reimbursed by Audi HQ if it doesn't solve the problem.

I'm not 100% sure about the gear position switch, though I think it was OK.

I've read of other stop/start systems where the engine always stops in a particular crank position, to allow a quick and easy restart. Do you know if the Audi system works like this?

 

[josedebardi]

I don't, but it would make sense, there is of course a crank position sensor so if that is playing up that could explain it. As I said initially there are a ridiculous number of possibilities. I think you will just have to let the techs do their work, my idea of another dealership was you never know if another Master Tech may have come across the issue before - it's not unheard of for one dealership to spend weeks diagnosing and then another find the issue in 5 minutes!

 

[slipped_disc]

OK, so it turned out that the problem was related to G701, the gearbox neutral position sensor. The service report states, "Traced fault to swarf on sensor. Cleaned sensor and tested OK".
Apparently by swarf they meant dirt, not bits of gearbox. Anyway, wife happy to get her car back!

 

[josedebardi]

Ah nice, so it was one of my many suggestions! Glad to hear it's been sorted with minimal fuss