P0172 P0175 System too Rich Bank 1 and 2

[TripleBlackZHP]

Hey everyone and Happy New Years!

So I recently threw a CEL, used a OBDII scanner and 2 codes P0172 and P0175(see below), the long term fuel trim is way out of wack. And a few weird things probably related, the idle when cold in the morning goes up and down maybe 50 RPM at random until warm, and it stumbled once or twice when giving it a bit of throttle(felt like a misfire) and once when I started it up(warm) ran weird for a few seconds, the car was vibrating (maybe misfiring) then it stopped and hasn't done than since, but runs nice when warm and other wise it seems fine. I've only had the car a few months so still feeling it out. It seem our cars don't often run rich (mostly lean) so its hard to find any resources online and the ones I do see say check the MAF, disa valve.. vanos...air leak and on and on. I will post OBD reader results below, any help to decipher OBDII to point me in a direction would be so awesome. Thanks, and I will keep you guys posted once I find the issue. 346233462434625

[RUS_ZHP]

P0172/75 are the codes associated with bad vacuum and clogged CCV. I had those codes in my car and after I overhauled entire CCV, they dissappeared.
If you car experiencing misfires, you would be able to see it on any basic OBD scanner.
My scanner tells me in which cylinder the misfire had occur.
I would clean the idle control valve and see if that will help with more stable idling. That procedure is pretty simple.

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[ZHPizza]

I was getting those codes after a stumble on the highway and it ended up being the fuel pump. Sounds like yours is more likely the MAF or O2 sensor since it's only one bank that has crazy fuel trims. Can you log the O2 sensor voltages with that app?

[Dave1027]

I had the same codes. Since my MAF was original, had a chunk of plastic missing and a slightly broken connector I decided to throw a new MAF at it. It's been two months and the codes have not returned (knocking on wood). I also notice the idle and acceleration seem a little smoother. I bought a siemans MAF from FCP for about $200.

[TripleBlackZHP]

I was getting those codes after a stumble on the highway and it ended up being the fuel pump. Sounds like yours is more likely the MAF or O2 sensor since it's only one bank that has crazy fuel trims. Can you log the O2 sensor voltages with that app?

Yeah I believe it can, I really haven't played around with it much. I guess if I can see activity there I can rule out bad O2 sensors?

[ZHPizza]

Yeah I believe it can, I really haven't played around with it much. I guess if I can see activity there I can rule out bad O2 sensors?They tend to get lazy and/or erratic when they go bad, so if you can plot it you'll be in good shape. Since your problems are at idle, definitely see if you can get a reading from the MAF (the Torque app will do this) to compare with normal. I can get the idle value from mine tomorrow.

[TripleBlackZHP]

Thanks for all the replies, I will have to dig a little deeper and maybe log some activity. I work all week so will post my finding this weekend. I am leaning towards MAF because this car was in a front end collision a year or so before I bought it, so maybe they replaced it with a cheap MAF or it got damaged. I am hoping there is way I can tell with my OBDII scanner, don't want to buy a $200 part and not fix it.

[TripleBlackZHP]

They tend to get lazy and/or erratic when they go bad, so if you can plot it you'll be in good shape. Since your problems are at idle, definitely see if you can get a reading from the MAF (the Torque app will do this) to compare with normal. I can get the idle value from mine tomorrow.

OK thanks man, I will try to log some activity tomorrow. I have a decent app 'dash command' its a paid Iphone app but my OBDII is a WIFI one not bluetooth so I don't think torque works with it.

[TripleBlackZHP]

I had the same codes. Since my MAF was original, had a chunk of plastic missing and a slightly broken connector I decided to throw a new MAF at it. It's been two months and the codes have not returned (knocking on wood). I also notice the idle and acceleration seem a little smoother. I bought a siemans MAF from FCP for about $200.

how long did it take for your CEL go away after installing a new MAF?

[ZHPizza]

Thanks for all the replies, I will have to dig a little deeper and maybe log some activity. I work all week so will post my finding this weekend. I am leaning towards MAF because this car was in a front end collision a year or so before I bought it, so maybe they replaced it with a cheap MAF or it got damaged. I am hoping there is way I can tell with my OBDII scanner, don't want to buy a $200 part and not fix it.

Is there anyone in the area with a 330 that you could swap MAFs with? I have a new one in the box that I'd let you try if you were in the states.

Also check to make sure it's a VDO or BMW part. Knock off MAFs can cause a lot of issues over time.

[Dave1027]

how long did it take for your CEL go away after installing a new MAF?

I used an OBD2 scanner to clear the codes when I replaced the MAF. Before I had replaced the MAF I tried clearing the codes several times but they always returned.

[TripleBlackZHP]

I used an OBD2 scanner to clear the codes when I replaced the MAF. Before I had replaced the MAF I tried clearing the codes several times but they always returned.

That's good to know, I've tried clearing my P0172 and P0175 codes and it does't let me clear them at all, CEL just stays on.

[TripleBlackZHP]

So I’ve finally solved this problem, and long story short, thankfully it was just a lower intake boot (hooray!). It had a finger sized hole on the smaller tube that connects to the idle control valve(maybe why I got a rich code not a lean). I had a local BMW dealership diagnose the CEL ($200) because I was getting my airbag recall done anyways (that was free), BMW offered to do the repair for around $300 but since I can wrench got the part for $30(OEM part) online and saved myself some beer money. Engine light was cleared and it has been off for a few weeks. I've noticed the car feels smoother in first and second gear, and has more torque at lower RPM.. I started this thread a while ago but parts ordered online took forever to show up. I didn't originally suspect the intake boot because I had an e46 325ci with similar P0171 and P0174 (lean) codes and it was also caused by a ripped lower intake boot so kinda weird. Anyways if you get P0172 and P0175 CELs it maybe an air leak in the intake boots.