I am a recent owner of a used 2011 GS TD4 with 31K on the clock and love the car, however lately the stop/start function rarely operates. At first I thought it was because of the particularly cold temperatures together with running the fan, audio, etc. But recently as the temperature has warmed and I have purposely driven without any fan, audio, lights on, it still appears to be reluctant to operate. The handbook states that one of the reasons may be that the engine has not warmed up sufficiently, but the temperature gauge needle is central (normal).

How many miles required to reach operating temp ? Battery charge low?

When we first got the car in late december, the stop/start did operate on 3 or 4 occasions whilst my wife was driving. Since then nada.

I would be grateful for any comments.

Same with ours, but we do lots of very short trips so (a) the engine rarely reaches full temperature and (b) the battery is rarely fully charged (in fact I have to top it up with a charger once a fortnight or so)

Most likely the battery charge is below normal. Battery is about 4 years old and as the vehicle as done a relatively low mileage I'd guess it's done a lot of short journeys which will increase load on battery. I've got a 2011 which has done 525000 miles and stop/start works on a regular basis once all the parameters are met:

Outside air temp between 0 and 40 degrees c
Engine at normal operating temperature
Battery fully charged
No significant drain on battery from use of audio system and air conditioning system.

Full details in the Owners Manual.

Thanks for your responses re short journeys / battery as I suspected, but great to have it confirmed.

Long drive imminent!

A technician once told me that there are about 30 different scenarios involved in deciding whether to switch off the engine, he said it was generally a mixture of settings determined by battery voltage and condition, air temp, air con, lights, recent history, exhaust temp, is the car rolling (!). What this means of course is that there is no easy way of telling whether you have a fault or that none of the conditions have been met!

Hmm, as mentioned earlier I will undertake a good charging run to see if that changes anything.Then check resulting battery charge condition. A good run usually sorts things out.
Thanks.