Obd Code P0171

[Sporty540]

Hey all,

Thanks for any help you can offer-
1999 540i automatic - sport package - 110,000 miles
Code from OBD reads "P0171 Mod$11 System Too Lean Bank 1"
Seems to be running a little quirky - will 'surge' or 'lurch' when at a stop or during slow acceleration (idle up for a second, then back down).
Also, acceleration seems sub-par - not really as smooth as I remember it being.

Any advice on what to check for, and how to repair? used

Thanks!!

[Teh Prof]

Originally posted by Sporty540@Jul 12 2005, 10:56 PM
Hey all,

Thanks for any help you can offer-
1999 540i automatic - sport package - 110,000 miles
Code from OBD reads "P0171 Mod$11 System Too Lean Bank 1"
Seems to be running a little quirky - will 'surge' or 'lurch' when at a stop or during slow acceleration (idle up for a second, then back down).
Also, acceleration seems sub-par - not really as smooth as I remember it being.

Any advice on what to check for, and how to repair? used

Thanks!!

[snapback]361811[/snapback]

Well, "too lean" just means there isn't enough gasoline getting in there. Fuel injectors going bad? Fuel injectors dirty? Injection timing off? Hole in the gas line?

[tacroteau]

From your description it sounds more like your O2 sensors going. That will give you poor acceleration, and cause that trouble code.

Originally posted by 528iUOND+Jul 12 2005, 11:12 PM--><div class='quotetop'>QUOTE(528iUOND @ Jul 12 2005, 11:12 PM)</div><div class='quotemain'><!--QuoteBegin-Sporty540@Jul 12 2005, 10:56 PM
Hey all,

Thanks for any help you can offer-
1999 540i automatic - sport package - 110,000 miles
Code from OBD reads "P0171 Mod$11 System Too Lean Bank 1"
Seems to be running a little quirky - will 'surge' or 'lurch' when at a stop or during slow acceleration (idle up for a second, then back down).
Also, acceleration seems sub-par - not really as smooth as I remember it being.

Any advice on what to check for, and how to repair? used

Thanks!!

[snapback]361811[/snapback]

Well, "too lean" just means there isn't enough gasoline getting in there. Fuel injectors going bad? Fuel injectors dirty? Injection timing off? Hole in the gas line?

[snapback]361816[/snapback]

[/b][/quote]

[bad man working]

Only tow thing that’ll cause this:

1. O2 sensor for the left bank of cylinders has gone fault and is showing the engine as running lean
2. The engine has an air leak on the left hand induction system i.e. inlet manifold gaskets etc

[LOS]

Accoding to the manual and your model/year:

P0130 thru P0161 are oxygen sensor related
P0201 thru P0208 are injector related

P0171 thru P0175 (either system too lean(bank 1 or 2) or
system to rich (bank 1 or 2)).

When was the last time you replaced the oxygen sensors? From my experience
and research, I have concluded that the sensors last around 75K miles (if you put premium gas), the Catalic converter around the same. I would go to a small shop and FOR around $100, find out for sure the problem. The sensors go for around $120 each (4 required, although you only have to replace them in pairs/ front ones or rear ones). You can do the job yourself, it's simple. The catalic converter between $400-750 OEM. Cheaper if not OEM but I don't recommend it!

Good luck and let us know the outcome so other members can learn from it.

LOS

[Sporty540]

Originally posted by LOS@Jul 13 2005, 10:07 PM
Accoding to the manual and your model/year:

P0130 thru P0161 are oxygen sensor related
P0201 thru P0208 are injector related

P0171 thru P0175 (either system too lean(bank 1 or 2) or
system to rich (bank 1 or 2)).

When was the last time you replaced the oxygen sensors? From my experience
and research, I have concluded that the sensors last around 75K miles (if you put premium gas), the Catalic converter around the same. I would go to a small shop and FOR around $100, find out for sure the problem. The sensors go for around $120 each (4 required, although you only have to replace them in pairs/ front ones or rear ones). You can do the job yourself, it's simple. The catalic converter between $400-750 OEM. Cheaper if not OEM but I don't recommend it!

Good luck and let us know the outcome so other members can learn from it.

LOS

[snapback]362108[/snapback]

Thanks everyone - I'm going to replace O2 sensors to start. Hoping cat converter not bad because I'm looking to sell my baby and would prefer not to have another $800 expense! I'll see if O2 helps, and let you know!

[///Matt]

I know this sounds like a long shot, but with the banks running lean, and the injectors weakening....+110,000 miles, I'd bet you have a vacuum leak....have your intake manifold gaskets tested...I had the exact same problem with my 540.