ACE Pump

I am constantly having problems with the ACE sytem on my Discovery,I have changed the ACE valve block and all the pipes and had the ECU re set.The warning light stayed off for a couple of weeks and has now come on again everytime the engine is started.
Could the pump be faulty and not pressurising the system,is there any way of testing it.
Thanks Lucky CB

is it the red or yellow warning light have a read of this to see if its of any help www.discovery2.co.uk / ACE amber light - Pressure Transducer