This keeps on happening on the Citaro facelift and facelift conversion on the bendy bus(one of the reasons why i don't like driving helvete's lhd citaro facelift) and it translates to "supply pressure too low" i assume it's for the brakes and i always receive it even i have revved the engine to achieve higher brake pressure(like on every other bus). So is there a quick solution to solve the break pressure problem?