On a 2005 Citroen C5 auto petrol it would act up in a very strange way:
Starting the car and doing several(2-5) kilometers (extra-urban) it would forcefully change to 2nd gear with a good kick and not go up or down, automatically or manually. The only thing that would 'fix' the problem is fully stopping and restarting the engine, after that it may not do it for another 2-3km or it may do it after 15km.
The issue intensified after changing the gear-box oil, before that it'd almost never do it, or if it'd do it a full stop - restart would fix it for the remainder of the trip.
Driving urban it'd not do it now or before.
Does the above described mean new gearbox ?
(no OBD codes)