My car has now got 25000 miles but, since its 20000 miles, it occasionally happens that, when driving, the speedometer drops to zero and the car loses power. I've tried turning the engine off and starting it again, but the failure persists. When I keep driving, the speedometer suddenly recovers by itself for no apparent reason. There are some months in which the failure does not appear and others in which it takes place twice a week. Does anyone know anything about it? Thank you in advance for your answers.

The automatic transmission jerks in my Peugeot 207 after changing the transmission fluid.