Does this occur when the vehicle is stationary or only when coming to a stop? If it is only when driving, have you got vehicle speed showing in live data? Had this on a 307 last month and it was a dead speed sensor in the gearbox. The Peugeot parts man tried to convince me it didn't even have one and that it used the ABS info. You wont have the seat belt warning beep either if you drive the vehicle with the seat belt unfastened if this is the problem. Pretty sure the 206 will work in the same way. Probably wont be your problem if it cuts out when you just rev the car but I wasn't sure from your post.

Liam