When driving normally, a warning sound and the screen tells me 'faulty gearbox', and the S * signs followed by a 'jerk'. If I stop the engine, then start it, albeit slowly initially, the car is 'normal again, until it happens again- could be after a mile or 100 miles. What is the trouble, and is it common ?

Ken, August 2013

Could just need a software update if you're lucky, but it could be a sticking solenoid that needs replacement.

See

http://www.howtomendit.com/answers.php?id=336707

ChicksFan, August 2013

We have a 206 auto and the Haynes Manual says it is fitted with a fluid wear indicator,the ECU causes the sport and snow light up when the fluid needs replaced or topped up and it has to be reset by a Pug dealer after top up.On the 206 the level is checked by a hex bolt set inside the g/box drain plug,it is a bit complicated for here.But it may just be that you are due a fluid change.Good luck.

Rich, August 2013