So,
I have a 2015 500L 1.3 multijet. Today, the start-stop function gave up on me. I use it in town, because I want to be green, one of the main reasons I went for this car. But, today, it simply wouldn't kick in. I tried all sort of "Eco" measures to see of it would kick back in, like driving with low revs, short shifting, coming up to the lights, with the car almost stalling, and still no action. Now, I know that the battery has to be above a certain voltage for it to kick in. It would usually kick in when the car is up to normal operating temperature. But. not today.
Am I doing something wrong? Is there a procedure to get the function back working? Or is this a dealer fix?
Thanks in advance

It's more than likely just that the battery wasn't charged above the threshold for start-stop to cut in. Mine will stop activating if I do a few short journeys too. A good run for 10-15 miles up & down a dual carriageway should sort it, but I wouldn't advocate wasting fuel & CO2 for the sake of it, unless you need to make the journey anyway.

If you do do a quick run on a dual carriageway or such like, I would deactivate start-stop until you've driven round at low speed for a few mins, as letting an engine cut out straight after a quick run isn't great for the turbo

My s/s ceased work a few weeks ago, left it a couple of weeks as brake service was due.
Tried all the obvious things like engine up to temp, air con off etc.
Told dealer of problem. Brakes sorted, report said s/s now working. Not when I got in car!
Back to dealer, it seems the diagnostic machine says s/s OK but it doesnt actualy work, so next week they will try again.
I looked at the old s/s thread, it seemed to de-generate into an I'm a better driver than you and dont need it. The fact is it is fitted to the car and should work. On selling your car watch the offer plummet when you say "Oh by the way"!
Be safe out there

Do you have automatic aircon?
If the car feels it's to hot or cold in the car, the start/stop system is disabled.
Same thing happens if the battery is low on power.

I'd go for a good run, at least an hour, preferably with a motorway run, driving in third in the thirty areas, fourth in the forty areas and also the motorways. In other words keeping the revs at 2000 plus for a good while. I suspect this could be another DPF problem!

Agree with the suggestions here. Had the same issue. where it actually came up with a red warning light about the Stop/Start function. Didnt bother too much with it but after a decent motorway run (30 miles or so each way) It seemed to work again fine. (Also refilled the AC Gas, but cant see how this could be related) Would think the Motorway run sufficiently charged up the battery and possibly had a dpf regen session.