C5 2001 2.2 hdi Auto only shifting to 2nd

[horsedentist]

Hi Guys

Well after several hours under and over the C5 virtually all the faults have now disappeared off of the lexia all I have left is a post heat fault and intermittent downstream cat temp fault. But the gearbox problem persists I have got rid of the engine torque regulation fault that was showing under the ABS and the speed faults.

I am now left with the following scenario under normal driving the car will only change up as far as 2nd except occasionally it will decide to work for about 2 or 3 miles then it will revert back to only changing as far as 2nd.

In manual the box works fine up and down no problems.

AND

If you get out on a dual carriage way and put the cruise control on it will work absolutely fine slow down to negotiate a round about accelerate away up to second hit resume on the cruise control and it will immediately change into 3rd and continue accelerating.

So what is it getting from cruise that it is not getting from my foot on the throttle??

Any thoughts no matter how silly appreciated.

Oh I checked oil level in the box and topped it off with about 750ml of fluid.

[horsedentist]

Any thoughts or words of wisdom