E9X Replace N55 power steering pump


Mar 25, 2022
Hello everybody,

I have a car 335i E90 {N55 PWG}.
My car's power steering pump was in a terrible condition. When I was rotating steering wheel, pump had a terrible noise (So big annoying sound + RPM was up and down and engine was not happy at all). I just replaced pump (Pump is used, but from another car), steering wheel became so much gentle (I felt hydraulic), no big noise of pump anymore (Even engine sound changed). But I still feel, that when I am rotating steering wheel engine RPM is shaking a little bit (Hard to note, but still happens). For instance, in neutral RPM is on 0,6RPM and if you rotate steering wheel it will become 0.7/0.8. If you rotate steering wheel left/right side very much (Once it achieves angle limit), engine is not happy I think (It has an annoying sound). RPM is shaking more, and sound (pump sound IMHO) is more visible.

1) Is it normal behaviour ?
2) After changing power steering pump, MHD shows me and error code (3225 - DMTL leakage diagnosis pump, activation: Short circuit to B+). What this error refers to ? Is it critical ? I tried to clear error codes, but still get the same in several minutes. I am interested in, is it critical ? If not, even this case I am interested to know how to fix this issue.

Thanks !