When I had that code pop up, accompanied with a rough idle, I replaced the camshaft position sensor and cleaned the two solenoids. That seemed to the trick, now it seems I’m throwing the 01554 code. I bought my sensor on FCP euro!
Did replacing the two vanos solenoids fix your P1554 code? I think that is the route I’m going to have to take. I cleaned the intake vanos and the code went away but when I am at an idle the rpms seem to go as low as 500 (should be about 600) and there’s a little shake. I also feel a loss of power went accelerating. For reference it is an 07 328xi N52 manual.