The customer took to dealer for code read,which came up with compressor unable to vent,quoted £700 to fix with new compressor complete,not happy with that he came back to us for another look,on the compressor it self there is an exhaust soleniod,which literally "vents" momentarally on system start up,if it cannot do this it logs this code.The outlet of this solenoid is to atmosphere through a small pourus brass vent about 1cm long,this part was blocked with scale from compressed air vapour,to overcome this all ive done is to drill a very small hole through the centre amnd hey presto fully functioning suspension & one happy customer,since found out in the US there was a product recall for a modifyed vent,$2.90! Dealers have no idea how to please customers!HTH keith.