Hi. I am new and having trouble navigating around here. But this is my question/problem. The start stop on my 2019 500x works for the dealer, but not for me. All indications from their computer read outs are fine and when they test drive the car they say the start stop works. It doesn’t work for me. The kicker is the start stop on the loaner car they gave me works for me. Am I living in an alternate universe?

Hi and welcome

Its a fussy system..
NEEDS great battery voltage
Loads like aircon etc all limit its effectiveness

My stop.start showed the typical:

Would work a few times after a long run.. then tailed off to nothing

This cycle continued for around a year.. no 'shutting down' since

However.. it would restart after a stall
So obviously still had the capability.

The motor only 'shuts off' if the sensors on the battery terminals are ok with the
Ratio of Battery Charge VS Electrical Load

A common sign is the 'paused' period of automated 'shut off' before an automatic restart gets shorter and shorter.

Until there isnt enough 'in reserve' for the system to permit a 'shut off'

My instinct says its an ageing battery.. possibly in combonation with little time spent with the motor running (charging)

My ageing battery got occasional charges at home which did keep the S:S in operation.. its possible the garage are doing the same


Tell us more

1. Silly question but....you don't have the light showing on the stop-start button just in front of your left hand when it's on the steering wheel?
2. How do you have your aircon/heating set? If that's working too hard it will keep the motor running
3. What do you do with the brake pedal when stopped? "Fiddling"/"Wiggling" (sorry - technical terms) your foot in a way that moves the pedal up and down will stop the system working
4. As above the battery needs to be well charged

500X Failed engine cut out conditions:

When the device is operating, due to comfort, emission control and safety reasons, the engine may not stop in some conditions, among which:

Engine still cold.
Battery not sufficiently charged.
Windscreen wiper at max. speed.
Particulate trap regeneration in progress (only for diesel engines).
Driver's door not shut.
Driver's seat belt not fastened.
Reverse engaged (for example parking operation).
With automatic climate control, if a suitable level of thermal comfort has not yet been
reached.
4WD low Active.
Heated windscreen active.

During our reduced driving due to the pandemic, both our cars (not Fiats at present) stopped engaging s/s. A 40 mile round trip got it going again in my wife's Renault, but it took a 250 mile round trip to kick the system in my Hyundai into life. These systems are very battery sensitive.