Auto start stop not always working?
 

This is driving me crazy. I can almost never get the auto start/stop to work for me.

I know that the button needs to be pressed (light off), the electrical load needs to be low and the car needs to be warmed up.

Even when the car is warmed up (213 degrees oil temperate is what mine seems to baseline), all the electronics turned off (sound, AC, headlights etc..), I still get the A with a cross through it symbol that specifies that the auto stop will not happen at this stop.

A couple days ago when I tried it however, it all worked. This was with headlights and a weak amount of AC on! When I brought it into the dealer, obviously it all worked.

I really won't be using this feature, but my factory warranty runs out in a couple months so I want to make sure everything is in working order!

It depends in a few factors, believe it or not the seatbelt has to be locked, outside temp (has to be cool) and a few others that escape me, have to align for the feature to work.

The "outside temp has to be cool" catches my eye. I'm in Phoenix, AZ so its MOSTLY been 70+ here. It could be possible that the times it worked it was lower though.

I know I have tested it when its like 72 outside. Could this be the reason??

Happens to me with my Cayenne. Sometimes when I get a non branded gasoline, it does not work. Haven't spoken to dealer about it, yet. Very odd.

Do know when battery is not fully charged, it does not shut off either, which is normal.

Don't think is temperature related.

Well today at the beginning of my drive it worked and it was 80 degrees outside, so its not temperature. Interestingly, later it did not work again!

Whats the battery supposed to be at? When I look at the battery voltage through the dash screen, I think it was at 14.4V.

As for gasoline, I fill up with nothing buy 91 at shell.

Off of the Owners Manual, I hope this helps.

Auto Start Stop Function:

The engine stops automatically when the vehicle is
stopped, e.g. at traffic lights or in a traffic jam.
The Auto Start Stop function thus helps to
save fuel.
The ignition stays on even when the engine
switches off automatically. All safety functions
are still available.
Stopping the engine
The Auto Start Stop function stops the engine
as soon as the vehicle stops moving.
1. Use the footbrake to hold the vehicle in place.
2. Keep the footbrake pressed.
or
Move PDK selector lever to position P.
Preconditions for stopping the engine
– Engine compartment lid closed.
– Driver detected: driver’s seat belt fastened and
driver’s door closed.
– PDK selector lever in position D, N or P or
transmission range 1 or 2 selected manually.
– Engine, transmission and battery are at
operating temperature.
– Vehicle was driven at a speed of more than
approx. 1 mph (2 km/h) for at least
1.5 seconds since the engine last stopped
automatically.
Starting the engine
The Auto Start Stop function starts the engine:
f In PDK selector-lever position D, N or manually
selected transmission range 1 or 2:
Release the footbrake.
or
Press the accelerator.
or
f Move PDK selector lever to position R.
You can drive off normally.
Note
The engine will start automatically in certain
situations, e.g. if the vehicle starts rolling, if air
conditioning causes reduced comfort, or if the
brake booster vacuum is reduced.
Starting the engine manually after leaving
the vehicle
If the driver’s seat belt is unbuckled or the driver’s
door is opened after the engine was stopped
automatically, the engine will not start
automatically.
Furthermore, if the brake is released, the engine
has to be started manually.
The message “Please start engine manually”
will appear on the multi-function display in the
instrument panel.
f Please see the chapter “OVERVIEW OF
WARNING MESSAGES” on page 152.
Exceptions for the Auto Start Stop
function
The Auto Start Stop function is not available in the
following situations, for example:
– When Sport mode is activated.
– When PSM is off.
– In Maneuvering mode.
– When AC MAX mode is activated.
– When the “Windshield defrost” function is
active.
– While adjusting the chassis level.
– When the rear fog light is on.
The Auto Start Stop function is available with
limited functionality in the following situations,
for example:
– If the air conditioning or passenger
compartment heating is operated at a high
setting or if the defrost function is run for long
time periods.
– If the battery charging condition is low.
– On upward or downward slopes.
– During internal vehicle test procedures,
e.g. automatic engine checks.
Note
If one of these situations arises after the engine
has stopped automatically, the engine can be
restarted automatically.

I've read that before, however it seems like none of those conditions apply and its still not working! Oh well I suppose.

I remember that the only way it would work for me, was when it was cool outside or I had the AC off, I will give it a try again and report back.

If you doing short driving, it will not work as battery is not fully charge.

Ooo ok, so this might be it. Most my drives are relatively short (less than 20 minutes). What charge on the battery would I be looking for to know its fully charged? Like I said, last time I looked when it wasnt working, I think it was 14.4V

When i bought mine I was worried as well, it happens to me all the time, I did ask the dealer, they said if there is no light on in the dash indicating something is wrong then it is working. It is always temperamental as the on-board computer is computing for all the ideal condition for it to work. Sometime it works great sometimes it goes missing for days. So when it works I'm just happy, when it doesn't ...oh well!!! Doesn't mean it is faulty or not working. These are sophisticated machines with complex computers on board.

Well I finally proved to the dealership that something was wrong. I took them for a test drive and showed them that all the qualifications were met and it still wasn't working. So this time they actually did some testing and digging and saw that every time it wouldn't turn on because of low voltage. Even though the battery voltage in the car showed as good. They charged the battery and it was good to go. They said because the last owner rarely drove the car, the battery must have drained a bit and that these cars do a bad job or recharging.

So if yours isn't working, don't take no for an answer, make them check the codes of why! There is absolutely no "mystery" to it. After they fixed it, if I'm buckled in and the car has been on a COUPLE minutes it works. Even with the AC on, headlights on, music on etc.. It just works EVERY time I stop.

Thanks for update. I thought it was the battery not being fully charged as it was same for mine.

Thanks for the update, I'm going to have mine checked as well!!!!

Well it stopped working again... Now it looks like my running volts is around 14.2 instead of the 14.4 that I would see earlier.

I hope they don't try to blame this on the battery, which is warrantied. the battery hasn't shown to give any problem like with starting the car.

Seems like its the alternator isn't doing its job of charging the car while driving. I drive it everyday and not just for short trips, so it gets plenty of time.