The Range Rover EAS has two fault modes known colloquially as 'Hard Faults' and 'Soft Faults'
A Hard Fault is when the system lowers the car to the bump stops and the ride is Hard (Hence the name)
A Soft Fault is when the system retains a ride height but indicates a fault.
The difference between the two types of fault mode is what has caused it.....usually a Hard Fault is an Air Leak of some kind or lack of Compressor running.
A soft fault is more often than not a faulty Height Sensor, sticking valves, or tripped thermo switch on the compressor.
Two ruddy fantastic members on here are pretty much the defacto experts on the EAS and they are Wammers and Datatec.
The Latter can produce a special cable and provide software (from a company called RSW Solutions) for only a few sheckles, this can then be plugged into the ODBsocket and read the fault codes. clear faults and calibrite height sensors....
He is on Holiday till the the end of the month I believe, but send Datatec a PM if you are interested in a lead and software disc....as this is the first place to start with a 'Soft Fault'