On top of the lumpy changes (suspect the valve block) I now have P0734 and it won't shift into 4th.

Looking through various threads it could be related to the valve block.

Any thoughts? Do I need to swap a whole block or just one solenoid?

Just the offending solenoid valve. When was the box fluid last changed?

Thanks. I'll have a look at Rave etc and see if I can identify which one it is.

The fluid was changed when the recon box was fitted 30k ago.

So after checking the solenoid values at the gearbox ECU I find the brake duty solenoid is out of range by a decent amount [supported by the lumpy changes but all shift solenoids are within range [just on the higher end].

After a few days of abandonment on the drive it's now decided to shift happily when cold, I am looking to take it up the hill that gave me the issues later tonight to see if the issue returns.

I need to get it in to the gearbox specialists next week for the solenoids to be changed.

As an aside, 2 weeks later and the 'specialist' who left me with the error and non-functional box has still yet to call me to discuss his findings and repairs!