Hello guys- I am new here and just looking for some advice!

I purchased a second fiat 500 1.2 Lounge 3 months ago, and I love her! Her name is Frankie and we are very happy together

But.... she obviously has the stop/start function which i am aware I can deactivate, but generally I forget as if I want it deactivated I have to do so every time I get in the car, which first thing in the morning is more than my little brain can handle.

2 days after getting the car the S/S kicked in when I was in traffic on a bend and never having encountered it in previous cars, i was momentarily blindsided and panicked and swiftly decided that until i felt more confident, I would keep it deactivated. I would forget occasionally, but S/S didn't seem to kick in over the next few weeks. Having come on these forums for a nosey, I simply assumed that it didn't kick in due to weather/heater being on/short journeys etc. and wasn't overly concerned. Might be worth noting that this was the only time in the last 3 months that the S/S has kicked in for a prolonged (standard?!) period of time.

Skip to the last 4-6 weeks, the S/S, if still activated, does kick in occasionally but almost as soon as the engine cuts out, the engine kicks back in. I would say within less that 10/15 seconds- as far as I am aware I am not activating it to do this myself. (although I am still a little confused as to how it all actually works! )

I've been reading through the forums and other S/S threads, and all seem to point to the battery being the issue, but I can't find a thread with my exact problem, so unsure if this is the actual issue or if I might be missing something (if there is one that I have missed - happy to be pointed in the right direction). I could just take it to a garage for their opinion, but I'm not overly trusting of them and their advice (and the costs that follow) so thought this may be the best place to start. Any help/advice will be very much appreciated- TIA Emma and Frankie

S/S in the 500 is frankly a load of poo. In later cars a button press leaves it off until you switch it on again but like yours you have to press it every time to switch off which is annoying.

It will activate randomly when so many variables are perfect especially if you have a brand new battery. There’s not much you can do about it.

Just get used to switching it off every journey.

The only thing you can do to stop it permanently is to deactivate it if you can find anyone nearby that has multi ECU scan.

Thank you for your reply typecastboy... so you don’t necessarily think there’s anything wrong with the battery that would necessitate me replacing it with a new one?

The system works just fine if all the various sensors are working and correctly aligned, if the battery is in tip top condition, and there are no other issues with the car. It will, however, stop working, or work intermittently, if any of these prerequisited are compromised. Something as simple as fitting a tail light bulb with an out of tolerance resisitance can be enough to put it into a hissy fit.

Personally I'd agree with those who think Fiat's S/S implementation isn't worth the hassle and the car would be better off without it.

That said, this sounds like a battery issue to me. If your car still has its original fitted (there'll be a date stamp on it somewhere), then just replace it and take it from there. Don't bother testing it; they can test just fine, yet still not be sufficiently close to 'as new' specification for the S/S to work correctly.

You do need to replace it with a battery specifically rated for S/S use. Sadly, they're not cheap; a shade under £100 if you shop around. If you want trouble free S/S operation, perhaps best to replace it every couple of years as a matter of routine (if you can stomach the cost; it likely won't save you much in fuel).

As JR says, it is most likely the battery has lost its edge. My car was behaving in the manner you describe when I bought it, new, in 2013. The S/S, when it worked at all, would stop the engine and then quickly restart it within seconds. A battery monitor showed the voltage dropping rapidly as soon as the engine stopped till it reached about 11.9V when the engine would restart. I have to say that, unlike typecastboy, I found nothing random about it; in fact it was quite predictable, and all the more annoying for that.

My car was a 10/12 build, obviously after they changed the S/S system so you don't need to keep switching it off every time. The car was sitting in storage for up to ten months without charging and it's most likely this drained the battery, causing the issue.

After twelve months of fighting a rearguard action, FIAT agreed to change the battery, whereupon the system immediately started to work to specification. The battery they fitted turned out not to be a S/S type yet worked the system faultlessly for three years. When it started to show signs of the same behaviour I replaced it with the proper type; an EFB (Enhanced Flooded Battery); not easy to track down in this country.

I'm pleased to say that as my car approaches the end of it's sixth year on the road it continues to run reliably and is a pleasure to own and fun to drive.

I’ve got a 66 plate 500x too with a fairly new battery. Since I’ve had the car the S/S has never worked which just saved me pressing the button to turn it off. A couple of weeks ago I stopped at some lights and it worked. Hasn’t worked again since.

If it bothers you having to press the button then as JR says invest in a new battery otherwise just leave it. If you do get a new battery don’t chuck the old one, keep it as a spare or give it to someone who has a car without dreaded stop/start.

My 2014 plate never worked either until one day I found out that my battery failed on me, purchased a new one and it worked 1st time.

Mine didn't work so I got a new battery, which did the trick, but it wouldn't stay stopped for long.
Then the clutch pedal sensor broke, and a new pedal got it working again.
Then the oil pressure sensor failed, which I had (expensively) changed, and the annoying warning light went out, but the SS hasn't worked since.
Oddly, if I stall it automatically restarts.

I'm normally fussy about having everything work on a car, but the SS isn't worth the hassle, as long as the warning light isn't on (which might be an MOT fail nowadays).

loserscar said:

Mine didn't work so I got a new battery, which did the trick, but it wouldn't stay stopped for long.

Then the clutch pedal sensor broke, and a new pedal got it working again.

Then the oil pressure sensor failed, which I had (expensively) changed, and the annoying warning light went out, but the SS hasn't worked since.

Oddly, if I stall it automatically restarts.



I'm normally fussy about having everything work on a car, but the SS isn't worth the hassle, as long as the warning light isn't on (which might be an MOT fail nowadays).

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I had it on and the tester asked me what it was and I told him. He just said “oh, ok”.