hi all, just had same sympton and same code,there are two valves at the back of the pump,the one closest to the block is for temprature and the outside one is a suction valve,i think they use this to reduce/control flow rather than dumping pressure ,anyway these are available from dealer,but once fit system requires recalibrating,dealer can do this for about £70,i have 7 differant common machines and none of them will do this yet.i wonder if just a recal would cure this ?, valve cost £130 ish.hope this helps.