Welcome to Bimmerfest -- The #1 Online Community for BMW related information! Please enjoy the discussion forums below and share your experiences with the 200,000 current, new and past BMW owners. The forums are broken out by car model and into other special interest sections such as BMW European Delivery and a special forum to voice your questions to the many BMW dealers on the site to assist our members!

Please follow the links below to help get you started!

Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 3 Series / 4 Series > E46 (1999 - 2006)

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

Reply
 
Thread Tools Display Modes
  #1  
Old 07-15-2014, 07:58 AM
mikeBMW1 mikeBMW1 is offline
Registered User
Location: MA
 
Join Date: Feb 2014
Posts: 13
Mein Auto: BMW 3-series
Oxygen Sensor confusion

I have 2 codes, P0171 and P0174, which both point out possible oxygen sensor failures in banks 1 and 2. My question though is how can I tell whether I need the pre-cat sensors or the ones after? And are the sensors for pre-cat (or after) the same despite different banks? Say, if I bought 2 pre-cat sensors for bank 1, would the other work for bank 2? I'd really appreciate any help!
Reply With Quote
Ads by Google
  #2  
Old 07-15-2014, 08:20 AM
1972ford's Avatar
1972ford 1972ford is offline
Function over fashion
Location: NH
 
Join Date: Jun 2009
Posts: 767
Mein Auto: 325xiT
I believe the sensors are different pre- vs. post- cat, however they are not different between banks 1 and 2. So the pre-cat sensors are interchangeable with each other. And same with post-cat. But not pre to post.
__________________
Reply With Quote
  #3  
Old 07-15-2014, 08:22 AM
mikeBMW1 mikeBMW1 is offline
Registered User
Location: MA
 
Join Date: Feb 2014
Posts: 13
Mein Auto: BMW 3-series
Thank you very much that helps out a lot!
Reply With Quote
  #4  
Old 07-15-2014, 08:57 AM
hexy27's Avatar
hexy27 hexy27 is offline
GO FLYERS!!!
Location: Charlotte, NC
 
Join Date: Jul 2008
Posts: 313
Mein Auto: 2002 330i
I may be wrong, but I believe O2 sensors have their own error codes. The lean codes you show generally point to some type of vacuum leak.
Reply With Quote
  #5  
Old 07-15-2014, 10:09 AM
Mirawho Mirawho is offline
Registered User
Location: US
 
Join Date: Jan 2013
Posts: 20
Mein Auto: 325i
Hi Mike. Like Hexy said, this is a lean problem. This could be the system trying to compensate for an air leak after the MAF adn throwing the lean codes. I would look there before going under the car. Check your vacuum lines. BMW vacuum lines seem to deteriorate fast. Could be the air intake hose past the MAF. Those boots crack too.
Reply With Quote
  #6  
Old 07-15-2014, 10:54 AM
cvx5832 cvx5832 is offline
Officially Welcomed to the 'Fest
Location: Walnut Creek, CA
 
Join Date: Jan 2009
Posts: 459
Mein Auto: 325Ci, 325Cic, C300
As pointed out, those are lean codes, not "bad o2 sensor" codes.
__________________


Reply With Quote
Reply

Bookmarks

Tags
2001 325ci, oxygen sensor


Forum Navigation
Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 3 Series / 4 Series > E46 (1999 - 2006)
Today's Posts Search
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On



Forum Jump


All times are GMT -7. The time now is 01:00 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
© 2001-2011 performanceIX, Inc. All Rights Reserved .: guidelines .:. privacy .:. terms