I had that code few times but only once it trigger SES (dealer checked the valve - and no parts were replaced at the time). As any code it needs to be there for number of cycles - if it clears itself indicating not present condition over allowed amount of cycles it will not trigger SES. 4D35
AnE934fun is absolutely right about un-experience of some dealers.
2010 335d e90
300, LCAD, ZPP, ZSP, 2XA, 302, 465, 494, 4B9, 609, 655, 677, 6FL, 6NF