2003 Renault Espace Mk4 headlights

I have a bi-xenon light system and the hi beams are fine but both the low beams are too low. Usually on start up you can see the level of the low beams swing high and then level off. When they are turned on the low beams stay at the lowest setting which is too low for driving on. The high beams are working OK and flash OK. This problem had a sudden onset with no previous symptoms.
Any clue as to what is wrong or what can be checked.