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Discussion Starter #1
Hi guys,

I recently my "Service Engine Soon" light is on. I took the car to the local auto store and pulled these codes from it.

P0171 Bank 1 too lean
P0174 Bank 2 too lean
P1083 Fuel control limit too lean Bank 1 Sensor 1
P1085 Fuel control limit too lean Bank 2 Sensor 1
P0313 Misfire has occurred with low fuel

My vehicle is a 2003 325I with 92K miles on it. Any advise you guys could give me beyond that would be greatly appreciated.
 

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codes

Hey check your intake boots (both) any small cracks in the rubber will give you vacume leaks and give you those codes
 

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Sounds like the classic symptoms of a vacuum leak; check your lower intake boots and get a smoke test done as soon as you're able. Just my two and a half cents worth...
 

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Discussion Starter #4
Sounds like the classic symptoms of a vacuum leak; check your lower intake boots and get a smoke test done as soon as you're able. Just my two and a half cents worth...
What is smoke test? Why you say soon. Will it make other parts go bad?
 

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The sooner you get a smoke test the sooner you will discover or uncover the vacuum leak. A smoke test is where the mechanic blows smoke through the vacuum system in order to find the leaking hoses. It could either be something as simple as lower intake boots or as complex as crankcase ventilation hoses. No the problem won't get worse nor cause other parts to malfunction, its just that most folks are in a hurry to get back on the road...
 

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Im dont want to start yet another running lean topic, so ill add on here. If the code is bank two only and intake boots are fine, does that indicate an o2 sensor?
 

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not necessarily... i had bank1 only lean and it was intake boots, O2 sensors RARELY go bad.
 

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Discussion Starter #10
Could be a hose connected to the intake boot with a crack. And did you actually take the intake boots completely off and inspect them or just give a quick look through the engine bay?
I took out intake boots and looked. Which hose you are talking about?
 

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I took out intake boots and looked. Which hose you are talking about?
Check both F-tube lines coming off top of intake boot sometimes they crack...very cheap to fix like un 2 doll hairs
 

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Another cause of P1083, 85 and P1071, 74 codes is the break booster

After chasing the lean codes on both Banks 1 and 2 and after replacing the following:

All rubber hoses
Valve cover gasket
CCV valve and pipes
O-ring dipstick
O-ring DISA
MAF
Upstream O2 sensors

I finally found the cause of lean codes, the break booster. Finally it dawned on me that hissing in the cabin when pressing the break could be the cause of vacuum leak.
Running diagnostics, the short term trim on both banks topped at 27%. Took a piece of rubber hose and caped it air tight and I plugged my break booster hose into the capped hose. As soon as the leak was caped the short term trim started to come back down and finally I started seeing negative trim values which I haven’t seen in a long time. Furthermore, I started seeing long term trim values being updated, which I haven’t seen that behavior since the issues started.
Replaced brake booster and problem solved!!!!
 

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Yes bumping the thread

Yes I am bumping the thread since my interest is to grow the communities knowledge base through short and concise solution, unlike some solutions that are full of fluff and misinformation.

Barely a couple of hours past since my post and you are complaining. Are you trolling or protecting something? Let's be less egotistical and focus on helping out people.

Furthermore, if you would have written more concise posts like I did, where specifically mentioned Lean codes are possibly related to a bad break booster. This way search engines like Google would return in the results when one searches lean codes P1071, P1074.
 

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Yes I am bumping the thread since my interest is to grow the communities knowledge base through short and concise solution, unlike some solutions that are full of fluff and misinformation.

Barely a couple of hours past since my post and you are complaining. Are you trolling or protecting something? Let's be less egotistical and focus on helping out people.

Furthermore, if you would have written more concise posts like I did, where specifically mentioned Lean codes are possibly related to a bad break booster. This way search engines like Google would return in the results when one searches lean codes P1071, P1074.
:thumbdwn:

Jeno my friend, please do your homework.

Lets see, I am a "troll", "egotistical", not helping people out, posts full of fluff and misinformation. Well I think you need to spend a few hours reading over many of my posts here and I think your eyes will be WIDE open and you will learn far more than you ever would want to know about problems with your E46. I have over 16,000 posts on this forum alone and I am involved in many other forums, so this is not my only place I call home. I doubt all of my posts here are troll posts, full of fluff and misinformation, I would probably be banned from this forum if this was the situation.

I do not typically put Lean Codes (P0171, P0174) in the title of my threads. SO many things cause Lean codes, but I typically put more info in the body of my posts. Also keep in mind the art of searching and doing research is just that, it is an art. You need to spend time doing your research using multiple ways to search, multiple key words, search using search engines and search using the forum search tools. BTW, over 5,000 views on the Brake Booster thread alone in 1 year! I have other threads with over 200,000-300,000 views.

You have a whopping 2 posts to your credit and just signed up here, you might want to post that you have also replaced the power brake booster in the thread I have on bad brake boosters so people can see that this problem is a real problem and more and more of these power brake booster are failing.
 

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trying to pass inspection - first codes I had were misfires so I figured full tune up - plugs- ccv - valve cover gasket (was leaking) - intake manifold gasket and new vacuum cap on back of intake manifold - no more misfire codes - got 02 sensor codes - so replaced post o2 sensors - no more o2 sensor codes - secondary air code was next - started replacing vacuum lines - that little valve on the back of the intake manifold - and big hose from secondary air pump - no more secondary air codes - then came the lean codes p0174 and p0171 both banks - hmmm - did I say full tune up? didn't do the fuel filter - which also has a vacuum line - yay. But no! did the fuel filter and vacuum line and still lean codes - did the maf sensor - car ran worse! more lean codes of the p0185 p0183 variety and the p0141 and p0174 remain! So I do the basic spray around with card cleaner and nothing seems to be leaking. I thought I covered everything. I probably need to have it smoked. But... what do you think - DISA valve? Pre 02 sensors? Is my new maf sensor defective or just more sensitive? the car is hard to start now - never had that. Is the position of the maf sensor important? does the box need to be on top - mine is to the side. Also - I have a cone filter in place of the oem box if that matters... HELP! Is it possible to put the fuel filter in wrong? Can't thing of anything. Oh yeah - it was taking forever - drive cycles galore to get evap to clear - new gas cap and everything seemed to clear faster but now these latest codes are immediate - a little less than 1/4 tank of gas in there now. Sorry for the long post but need help ASAP! Haven't checked brake booster yet...
 

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Hello everyone,

I just purchased my first 2003 e46. A couple months ago. Current milage 144,xxx miles I currently got a check engine with codes p1082, 83 and 85. Can some one please point me to the right direction as to what can cause these problems and where to begin looking? Much thanks!!
 

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Hello everyone,

I just purchased my first 2003 e46. A couple months ago. Current milage 144,xxx miles I currently got a check engine with codes p1082, 83 and 85. Can some one please point me to the right direction as to what can cause these problems and where to begin looking? Much thanks!!
Are you sure about the p1082? I don't see it listed on obd-codes.com

The p1083 & p1085 are lean mixture codes, either caused by a vacuum leak (too much air) or possibly a bad soft failing fuel pump (not enough fuel).

Intake boots, especially the lower one with the little tube to splits off to the idle air control valve, are a commons culprits. But a cheap cigar smoke test is also a good way to identify vacuum leaks:

 
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