Auto stop in hot weather

[Warthog21]

My new A6 MY17 is being looked at because the auto-stop system is not functioning and, indeed, has hardly worked since new. I took technician for a short drive and he suggested happened because the ambient temperature is high (25 deg) and the auto-stop will not work while the cabin is being cooled down by the A/C. Has anyone had similar problems? The car is being kept in overnight so I might get a decent drive in the 3.0l Quattro Sline tomorrow.:D

[Eshrules]

My new A6 MY17 is being looked at because the auto-stop system is not functioning and, indeed, has hardly worked since new. I took technician for a short drive and he suggested happened because the ambient temperature is high (25 deg) and the auto-stop will not work while the cabin is being cooled down by the A/C. Has anyone had similar problems? The car is being kept in overnight so I might get a decent drive in the 3.0l Quattro Sline tomorrow.:D

If that's the reason then yes it applies to every stop/start system I've come across - the AC can't cool the cabin effectively in high(er) ambient temps if the engine is stopped.

Easiest way to check that element would be to turn off the climate control so the AC isn't being used?

[AT.]

I took technician for a short drive and he suggested happened because the ambient temperature is high (25 deg) and the auto-stop will not work while the cabin is being cooled down by the A/C.

The MMI controls the electric systems in your car, and if the battery is low, or it could be discharged, then the start/stop will be disabled temporary. As the climate unit is one of the most higher power consuming unit in your car, it is able to discharge the battery very soon, so it seems a reasonable answer, that the start/stop will not activate when you want a huge cooling job.

However, with a fully charged battery the start/stop will work even in far higher temperature for a short period, and only after this period will the engine start up. IMHO the 25°C is not a so high temperature to not to let the start/stop system work at all. In my case, I can confirm that even a far higher temperature, the start/stop is working with a fully charged battery. If the battery is not fully charged, then the start/stop will not work at all.

If you feel, this could be your problem, the testing is very simple: turn off the climate unit, and check the start/stop. If it will activate itself, than the climate unit needs more power, or your battery is relatively low to allow the start/stop system to work. You can test it with a higher interior temperature setting, if you need a minimal cooling, than the start/stop should work without any problem.

[Guest 2]

Disable the start/stop completely .. It's a pain in the backside!!

[M1tchy]

Exactly what AT. Says. Try that and see what happens. Also if your car is trying a DPF regen it won't cut out.


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[Mr Magoo]

I was taking notice of what mine was doing today, and with drive select in Economy mode (my default) with AC on, music turned up (as normal) with c25 degrees outside, the car was activating the start/stop. When it was stopped, the AC automatically turned off, the fan slowed down, the music turned down too. It seamed the car went into power saving mode to enable stop/start to function to activate.

So based on this, yours not activating would suggest something is not right.

[AT.]

When it was stopped, the AC automatically turned off, the fan slowed down, the music turned down too.

Honestly, I never seen this behaviour


It seamed the car went into power saving mode to enable stop/start to function to activate.

Maybe it's a "new feature" in MY2017, just like the missing menu options... in my MY it works strictly the opposite way, if there is not enough electricity, then the start/stop will be disabled by the MMI and the engine wouldn't stops.

[ukgroucho]

Maybe it's a "new feature" in MY2017, just like the missing menu options... in my MY it works strictly the opposite way, if there is not enough electricity, then the start/stop will be disabled by the MMI and the engine wouldn't stops.

Probably it's because he has the drive select in Eco mode. Effectively in Eco mode you allow the car to decide what systems to run to get best economy - Start/Stop is an ECO feature so the car will sacrifice comfort features (like aircon) to enable Start / Stop to function as much as possible.
If you have the car in Comfort (or dynamic or auto) then you decide what eco features to use - and if you have the aircon enabled then you have prioritised that over Eco features like Start/ Stop.

[Chris81]

I know the start/stop function is disabled at certain points of using the a/c it heater.

It's in the manual showing what points it won't work. When the A/C is on low is start/stop will never work - that's for most VW's.


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[AT.]

If you have the car in Comfort (or dynamic or auto) then you decide what eco features to use - and if you have the aircon enabled then you have prioritised that over Eco features like Start/ Stop.

Yes, it's possible, that it's something new in MY2017, because I drove a lot my car in ECO mode, and I never seen this behaviour.

Honestly, I still don't think, it could be a good idea to stop the engine while the battery is low. For me, in a situation like this, it sounds a more reasonable thing to stop the A/C, the amplifier and so on, IF in the meantime the MMI lets the engine run, and charge the battery. If I remember well, it was the primary objective of the MMI's power management in my former 4F, so it seems possible, that due to new rules, it was changed to stop the engine all the time if it's possible, against to not let to discharge the battery.

[Splash]

Don't forget the AC has its own 3-tier setting (eco-intense in my MY14 car anyway). I leave it in "eco" for the Scottish climate but have used the most intense setting when temperature/humidity is uncharacteristically high (for my dogs, not me). Whether the eco profile is the same as is used in the "efficiency" drive select mode is anyone's guess.

[Hellfire]

Strangely enough, I had a similar problem earlier this week for a couple of days. At the weekend, shortly after starting the car on a couple of hour long journeys, I noticed a faint smell coming through the vents in the cabin. It was a sulphur type smell which I assumed was either catalytic converter or battery related. Shortly afterwards (Mon/Tues) I noticed the auto stop/start wasn't working. I tried everything to get it working again and turned off all ancillaries but nothing.

I assumed the two things were related and was preparing to call into my local Audi dealer to notify them of the fault but the auto stop/start began working again on Wednesday and has been working fine since. I put it down to the high temperatures on Mon/Tues but will keep an eye on it.

[Mr Magoo]

Probably it's because he has the drive select in Eco mode. Effectively in Eco mode you allow the car to decide what systems to run to get best economy - Start/Stop is an ECO feature so the car will sacrifice comfort features (like aircon) to enable Start / Stop to function as much as possible.
If you have the car in Comfort (or dynamic or auto) then you decide what eco features to use - and if you have the aircon enabled then you have prioritised that over Eco features like Start/ Stop.

This is why I mentioned the behaviour based on the mode the car is in, its could be affecting your situation..