I was pulling the same codes, my problem was the Disa valve o ring wasn't sealing, I rebuilt with the GAS unit. Basically you have an air leak somewhere, checks all intake hoses.

 

Those codes are classic codes for vacuum leaks. Have the intake smoke tested to find leaks.

 

I have the same codes, the dealer i bought my 325i from replaced the DISA, i drove the car about 1,500 miles and the lights came back on, im gonna check for leaks one day this week, ive read on some other forums that the Y on the lower intake boot right under the DISA is normally the culprit, good luck with your search!

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They are classic codes for a vacuum leak, however if you reset the code(s) and it doesn't come on at idle there could be another culprit that jfoj has noted and I experienced. If the code only come on intermittently and only at freeway speeds then you may not have an intake leak but a soft failing MAF. Odds are more likely a vacuum leak somewhere though.

 

cleared codes and drove for about 50 miles and the p0174 came back on.

 

915,

This is not how the game is played. You are providing NO valuable data.

Your car has a Lean problem, EVERY E46 has this problem in its lifetime. You can play Whack A Mole and try to fix one thing at a time or you can shotgun the problem and eliminate the obvious problems.

Suggest you read my comments in this thread - http://forum.e46fanatics.com/showthread.php?p=16727145

All the plastic and rubber under the hood should have been replaced by year 10.

Then this leaves the fuel pump and filter, the power brake booster and possibly the MAF.

We need to see Freeze Frame data, cold start data, warm idle and steady cruise Fuel Trim info. You probably have the wrong OBDII tool for the job, OBDFusion is the cheapest and easiest App to use to Log data and save 20-40 posts per thread.

If you read the items linked in my signature along with searching my user name you will see this is something we do to identify most of the problems wiht these cars.

 

Dont mean to thread jack, but as i posted i have the same problem, spent a little bit of time around the engine today. I noticed there is definitely a sucking noise coming from around the DISA, also when i remove the oil cap the rpms increase, does this mean anything?

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All these engines have a "sucking/vacuum leak" sound. This is due to the idle air bypass and the air distribution system.

Removing the oil fill cap will impact the engine RPM an idle.

Without having data, it is like throwing darts in the dark.

Smoke test and get OBDII data, Freeze Frame and warm Idle Fuel Trim info.

https://www.youtube.com/watch?v=AsgB9eBl58I

 

i thank you guy for all the useful information on this site.

i replaced both intake boots, injector o rings, dis valve o ring, TB o ring, all vacuum lines, intake gasket, oil housing gasket, dip stick o rings and she has passed calif smog with flying colors...reset readiness monitors in two short trips.

it has however thrown a couple of more codes...but it all part of the game...ill start a new thread on those.

thanks again.

dc

 

Ok after replacing the upper intake boot and checking maf sensor (I let a mechanic clean it with MAF cleaner) now it shifts rough like from park to reverse or drive its alittle jerky... any ideas? I know that the hose that leads into the upper intake boot the small one it has a crack in it im looking for the part...

 

Suggest you keep all your comments in your prior thread so help does not get lost in a thread with too many participants.

Might want to continue on in this thread you started - http://forum.e46fanatics.com/showthread.php?t=1100070

Seems you may have replaced the upper intake boot, this is RARELY a problem. Chances are you missed the obvious problems by a mile.

If you can get your hands on the original MAF sensors, get it back and reinstall it on the car. Most shops check really cheap replacement MAF's that DO NOT work.

 

Thks I have the original MAF sensor on it