AL4 problem when cold

[Anglebox]

Hi everyone
I have a 2006 2.0 HDI Peugeot 807 with the AL4 autobox
Problem is when cold it pulls away ok but then wont shift up and goes into limp mode (the engine revs up but no movement like a slipping clutch)
This normally happens within 1/2 mile from home
If I pull over and stop/restart engine it resets and is fine for the rest of the day (although it has started randomly happening when left for a short while)
I have changed both gearbox solenoids and changed oil (with the correct oil) 5 times now as a read on forum it could be dirty oil and 3 changes should sort it
The car has done approximately 75,000 miles
With full dealer service history
Is there anything else I can try or is gearbox fubarred ( had a suggestion to change pressure switch under gearbox)
Sorry to go on but wanted to give as much info as possible
Many thanks in advance
Regards
Steve

[ozvtr]

If I pull over and stop/restart engine it resets and is fine for the rest of the day (although it has started randomly happening when left for a short while)

This sounds like an electrics problem and not a clutch or brake problem. There are still other electro valves in the valve body, speed sensors and pressure sensors that you could replace.

Without a fault code however, you would just be replacing parts randomly.

You have a choice, start replacing more parts or seek professional help. In the very least try and get the car scanned and find out some fault codes.

Ok, just using probability as a guide, the next most likely thing to fail is the main pressure sensor. Now, without a fault code that's just a wild guess!!

[Anglebox]

Is that the one on the bottom of the gearbox?

[ozvtr]

Yes. It's disc shaped and has 2 mounting "ears" on it.

[Anglebox]

Thanks I’ll give that a go…..main dealer can’t get it booked in for another 9 weeks to scan it