I had exactly the same fault and symptoms. Used the diagnostic terminals and was line pressure solenoid valve.
£600 to fix and now all is well.
Bill.

Had the Bongo repaired. Line pressure solenoid. This is what came up when I used the diagnostic as advised on the forum. CODE 66. I had the fluid changed firstly because on the forum it was said that this sometimes cures the flashing light. The garage said they had trouble locating a solenoid. I ...

Had Auto Transmissions in Barnsley diagnose the fault and told a solenoid pack is needed. £700 plus vat. The unit is £500 so looking to have it done. Anyone had the same job done ?
Bill

Looked through the archives and fact sheets but still puzzled. The hold light came on and went into safe mode ( third gear ) I had the ATF changed and the filter cleaned as a first step and a 5 mile test run was fine. Next day after a short run the hold light came on again. If I stop the engine and ...