Error code P0155 Help

[yenanx5]

2001 x5 3.0L
OBD read P0155, but no SES light on. I been searching is Bank 2 sensor 1.
Could Expert out there Please help me to locate the sensor. Is it under the car or inside the engine compartment?
Thank you

[tonycajjo]

check all little vac lines under the hood. often ones cracked, epically since you have an 01.

[Weasel]

The fault code means bank 2 sensor 1 (O2 sensor) is reading a lean mixture condition. This doesn't mean you need a sensor, but you need to find the source of the unmetered air. Look for any place after the mas air sensor that air can get in, like the upper bend of the intake boot to the idle valve, crankcase ventilation valve and hoses, etc.

[yenanx5]

Originally Posted by tonycajjo

check all little vac lines under the hood. often ones cracked, epically since you have an 01.

Could you picture or show where are i need to look at?
Thank you

[Wayne's World]

1. Make sure you get the BMW code, not the OBD code to properly diagnose what's going on with your car.
2. Check out this thread on Vacuum leaks: Mixture too lean, P0171, P0174, P0313 - Bimmerforums - The Ultimate BMW Forum

[tonycajjo]

Originally Posted by yenanx5

Could you picture or show where are i need to look at?
Thank you

everywhere under the hood. vac lines and such are all over the place. anywhere between the MAF and O2 sensor. i would check along the intake there is a hose or two that attach to in on the bottom, also look up something called the main sucking jet.