My 2.5TD (BMW engine) Automatic June 2000 Facelift, regularly fails to change up from 2nd to 3rd Gear at the usual point (around 25mph?)
When this happens, the only way I can cure it is to take it on a road with a higher speed limit and just let it rev high enough so that it does change. This is usually accompanied by a bit of a jolt, followed by an 'Automatic Gearbox' failure message. After this message, I can stop the car, turn it off, wait a few seconds and then start up again and it will be fine - until a few days or weeks later when it does it again. This is the only way to be certain that the fault is fixed, albeit temporarily. On the odd occasion when it has seemingly sorted itself out and changed up, without the jolt and the error message, it usually fails again straight away at the next 'up' change.
I have recently bought (for spares) another Omega, the same year etc but it is a 2.5 V6 petrol.
I do not know if this is a gearbox fault, or an electrical fault but is there a component on the V6, that I could exchange to see if it fixes the problem?
Thanks