Age nearly 12 years
Mileage about 15000 (only did 5000 miles in first 10 years)
Always been garage maintained but nothing much needed
Current problem started about 3 months ago
Overtaking at about 60mph and engine moved to too low gear and high revs, After switching off completely and re-starting OK until reaching 50-55mph then problem recurred (but can goes for days without happening).
Yellow 'transmission' warning light comes on during problems.
Been to ex Rover garage 4 times:
1st time diagnostics showed problem in Speed sensor or in any of 4 wires.
2nd time. Wiring checked. Seemed ok afterwards for a while then recurred ... and at lower speeds (30mph) on 2 occasions.
3rd time: diagnostics again and suggested change speed sensor
4th time: changed speed sensor.
It seems to behave better for a while after each visit and then problem recurs.
Wondering if problem in wiring which is disturbed during tests. Garage suggests there may be an additional internal gearbox speed sensor.