2001 325i p0171,p0174 lean bank 1 and 2 codes - Bimmerfest - BMW Forums

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E46 (1999 - 2006)
The fourth generation 3 Series (E46 chassis) was introduced in 1999 and set the standard for engineering and performance during it's years of production including being named to Car & Driver's 10 best list every one of those years! ! -- View the E46 Wiki

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Old 04-05-2007, 01:42 PM
zatoich zatoich is offline
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Location: Queens,NY
Join Date: Mar 2007
Posts: 4
Mein Auto: 2001 325i
2001 325i p0171,p0174 lean bank 1 and 2 codes


Hello all, Well my story started with my sons 325i and the ck engine light. Yes lean bank 1&2 codes and a variety of missfire codes. I started with the fuel filter which needed replacement. I noticed quite a vacuum in the crank case.Some people said you should have vacuum and some not. Well to straighten out this mystery you ARE NOT SUPPOSED TO HAVE A STRONG VACUUM IN THE CRANK CASE. It should be very little vacuum with the oil cap off and just about nothing with the dipstick out. I have been a mechanic for many years and have very little bmw experience, however my sons 325i sure looked to me like a vacuum leak in progress. I checked the air intake tubes, the intake and every component with carb spray. No leak was found. I read once about a problem with oil separator valves. I went to bmw and dropped $62 down for one and went home to have a look under the hood. Needless to say I cant see anything that resembles the part. After searching the net I found a parts diagram and this valve is under the center of the intake manifold.The air adjuster must be removed on the intake manifold along with the air box all intake hoses,the wiring harness block and unplug most ends to be able to move the block out of the way,dipstick tube,throttle body,upper fuel rail trim cover.Now you can see ths oil/separator valve,two torx screws hold it on.There are three hoses on the valve.Replace all hoses with the valve.One hose on top of the valve goes through the intake manifold and twists on. It took one hour to install that one.The middle hose goes to the left side of the upper valve cover.Squeeze them together with your fingers to release.The third hose is on the bottom of the valve and goes to the dipstick tube.That hose is the cause of all the problems because it clogs up with crank case sediment and causes the hose to collapse under vacuum and then sends the valve off tilt and a great internal vacuum leak takes place in the crank case. After removing the diaphram in the valve it was also found torn. After changing these parts the car is running like a pedigree once again. Allow four or five hours for this job and a cup of starbucks. I hope this helps someone,

Last edited by zatoich; 04-05-2007 at 01:54 PM.
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Old 04-28-2011, 11:19 PM
Bimmerman512 Bimmerman512 is offline
Registered User
Location: Austin, TX
Join Date: Apr 2011
Posts: 1
Mein Auto: 740i, 740iL, 325i

WOW... from reading your story, I couldn't believe it.. I have NEVER had any crazy problems with BMW until recently...

I have owed outright 3 BMWs

My first...

Was a 1993 E36

It had 116,000 miles

It was White

It was all stock

It was Flawless

I bought it from a friend who's brother owns; (I say owns because he still does to date), a car dealership. I believe I was told it was a consignment vehicle which was owned an operated/maintained under a program at a facility otherwise known as Southwest Research. Based in San Antonio, TX -the 3-series was impeccable. Zero leaks, Zero problems, Zero regret.

My dad semi-religiously impounded into my head that Japanese vehicles: Honda, Nissan, Toyota blah blah blah was the way to go...

Yet, I bought a German.

I was happy with my purchase. I had fun with the car; I loved it.

Since then, the new trend had begun. I was a BMW FANATIC!!!!!!!!!!!

I bought BMW gear, blah ,blah ,blah and the works. Not to show off, but to support!

Years later, I bought my second BMW. I traded in my 3 series. which by then had over 275,000 miles, and bought a 1997 BMW 740iL. This car was immaculate! It had a $15,000 AC Schnitzer full exhaust kit from manifold to tail pipe! Another $10,000 body kit, again A/C Schnitzer! Alpine Rims, Dual Exhaust, 390 Horse Power, Zero leaks, However had cooling problems...

(turned out to be Heater Control Valve and ended up frying the engine)

You live, then you learn.... (not live and learn, impossible sometimes)
- what that means is sometimes it takes the life of a loved one to fully understand what is going on...


I then bought a piece of **** Mazda Millenia S

ended up liking some of the features but was not overall impressed.

My current BMW was given to me by my loving mother. She retired at an early age and cashed out $15 g's to buy herself a 2001 BMW 740i.

It was Ridiculously CLEAN!

and with Zero problems!

She drove it for a good year and a half (while I drove the ****ty Mazda) and then felt bad and gifted me the Vehicle.

Since then, I have had small repairs here and there because of the mileage which told me it was not properly serviced after all..

I am not certain IF these repairs were self inflicted or because of a prior owner. But to this day I am battling one thing after another.

I will NEVER give up hope on my vehicle.




That said and done

I recently replaced the OSV on my e38 and it was a simple yet, refreshing task I did on my own. I say refreshing because I did not have to remove any of the air intake pieces or anything else. In fact, there's an entire website, E38.org which is dedicated to the 7 series and repairs on DIY type projects. Which I give close to 100% of my BMW technicality experience to.

Tell your son to keep the BMW and move on up the series ladder. Because a Series tells the people where you stand in life. Even IF your son isn't a great master champ in life, it doesn't mean he can't live like one.
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