P0171 BMW - p0174 in bmw x3

Question

i found a vac leak and i fixed i bought a rubber part for intake manifold but after 400 miles the light came back again .so what can i do?

Answer 1

HI there,

This code can be the result of several things when they run together like this. I would suspect the mass air flow sensor and also check the fuel pressure. Because it's affecting both banks it's possible there is a problem like this that would affect the whole engine.