2004 X5 E53 vacuum line
 

Hi All,
My X5 was getting the error codes that both bank O2 sensors were trying to adapt beyond limits. This immediately led me to believe that there was a vacuum leak. Lo and behold as I was began searching, there was a vacuum line disconnected. It is the vacuum line that is attached to the dipstick tube. Does anyone know where that connects to? I have tried looking but cannot see any fittings that look like a vacuum hose fitting?

The only hose that goes to the dipstick is the oil drain hose from the bottom of the crankcase vent valve (cyclone valve) which is actually one of the common causes for a vacuum leak as well as an oil leak. It is #4 in this link.

RealOEM.com * BMW E53 X5 3.0i Crankcase-Ventilation/oil separator

Thank you very much for your response. I should have been a little clearer though. It is the vacuum line that is "secured to the side of the dipstick" not connected to it.

A picture if you can get one would help? Your brake booster hose (1/2") runs along in that area and connects to a regulator and then under the intake manifold.

SJBIFR,
I had same error codes (fuel adaptation limit) a few times last month. At first I thought vacuum leaking and tried to search around everywhere with no success. Finally, I changed the air filter and spark plugs and it does not come back for a month. Try this if you don't find any leak. I have 2003 3.0 62K miles.

Most common vacuum leak
 

Before getting started, I wanted to clarify quickly about the Oil dipstick hose that you guys seems having problem to locate up there.

There's only 2 hoses that connect to the Oil dipstick tube, the (big one#11) goes to # 10). And the smaller (one#13 goes to #13) NOTE: you can't even see where the smaller one connect to, because it's hiding in the back under the intake manifold. Nless you remove the intake manifold see pictures for details also for complete intake manifold removal...

sorry to resurrect the thread but i ave the same thing, it is in the are of the brake booster and it is clipped to the oil dipstick guide tube for routing purposes and about 3 inches up from ther it forms a u bend back down then terminates with no conncetion in sight, please help guys, i ahve a p0171 and p0174 and oil dipstick vacuum test seems good becuase when i remove it i get strong suction. thanks

Unplug the mass air flow sensor, if it runs better without it and more power,
replace it with a new one. And you should be good from there. However this was
my problem and I ended up removing the entire intake manifold for nothing.
But I realized after the problem was at the mass air flow sensor that turned
out to be faulty. Once I replaced it, codes are gone for 2yrs now, no check engine light.

Hey thanks for quick reply. I tried that just yesterday and the car idled crazy rough And put itself into trans fail safe mode. I do hear a slight whistle and doubt the ccv is bad. I did have valve cover gasket replaced 6 months ago but the codes were there before and after

Check the tube from the air filter to the intake. Sometimes the flexible elbow will get cracks and the air leak will cause those codes.
Spray WD-40 in the area with the engine running and if you get a surge of power, there's a leak.