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 > 5 Series > E39 (1997 - 2003)

E39 (1997 - 2003)
The BMW 5-Series (E39 chassis) was introduced in the United States as a 1997 model year car and lasted until the 2004 when the E60 chassis was released. The United States saw several variations including the 525i, 528i, 530i and 540i. -- View the E39 Wiki

Reply
 
Thread Tools Display Modes
  #1  
Old 05-09-2017, 04:27 PM
Sephiroth Sephiroth is offline
Registered User
Location: Fayetteville, NC, USA
 
Join Date: Apr 2017
Posts: 80
Mein Auto: 2002 BMW 525i
Arrow O2 sensors and ethanol...

I have yet to replace the failed O2 sensor on the 2002 525i that I purchased last month. Scanned codes today expecting the same old P0161, but I got more. I got the following codes.
  1. P0161 - O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 2)
  2. P0160 - O2 Sensor Circuit No Activity Detected (Bank 2 Sensor 2)
I also got a single pending code, "P2272 - O2 Sensor Signal Stuck Lean - Bank 2 Sensor 2". All point to the sensor after the cat for cylinders 4-6. I am replacing both O2 sensors on bank 2 soon. Waiting for payday first. I chose to replace both for the following reason.

90% of the fuel stations here are 10% ethanol (E10). I only run non-ethanol 93 octane in my vehicles, but this was purchased used and likely got gas from every station it went by, meaning ethanol contamination. This is likely what killed the sensor.

What happens is that some of the ethanol gets past the rings and into the crank with regular blow-by. What happens next can kill cats and O2 sensors. When ethanol is introduced into oil it causes the phosphorous to separate and get into the intake via the PCV system. I assume it is the same via CCV here with BMW. Anyway, this stuff doesn't burn well and winds up coating O2 sensors and the honeycomb in the cats. This reduces the life of the O2 sensor and can cause it to not read or even malfunction. Normally this happens over some time, not quickly. I believe this is what killed my O2 sensor.

With that in mind, I spoke with multiple techs including BMW techs. I let them all know I simply wanted their advice and that I would be doing the work myself. Every one said they would change them in pairs because if I stick a new one in that is working 100% and my old pre-cat sensor is only working at 50% it could cause issues and make the car think something is wrong. This makes sense. If there is blow-by of any kind coating the sensor, it should be changed with the other one, so I plan to do bank 2 this month and bank 1 maybe next month. Then all four are golden. I do not expect them to have issues nearly as soon if I keep the car long enough due to only running gasoline in it. E10 is actually NOT gasoline, it is gasohol.
__________________
2015 Ford F150 XLT 3.5 EcoBoost FX4 Off-Road
2002 BMW 525i
Reply With Quote
Advertisement
  #2  
Old 05-09-2017, 04:59 PM
pshovest pshovest is offline
BMW CCA 69606
Location: DE
 
Join Date: Dec 2009
Posts: 1,320
Mein Auto: '10 535i '08 X5 '00 528i
Ethanol has nothing to do with your problem. You have a failed sensor OR issue with power to O2 sensor heater. P0160 is a consequence of P0161
Reply With Quote
  #3  
Old 05-09-2017, 06:05 PM
540 M-Sport's Avatar
540 M-Sport 540 M-Sport is offline
Officially Welcomed to the 'Fest
Location: Seattle, WA
 
Join Date: Apr 2004
Posts: 5,952
Mein Auto: 01' 540 M-Sport, Scuderia
Quote:
Originally Posted by pshovest View Post
Ethanol has nothing to do with your problem. You have a failed sensor OR issue with power to O2 sensor heater. P0160 is a consequence of P0161
+1. I have the original post catalyst O2 sensors on my car. 16 years old and 266,600+ miles. I use exclusively (up to 10%) ethanol gas, as it is simply too far away and too expensive to use ethanol free gas (its is 40 minutes from my home and 80 cents more a gallon)

Ethanol can cause issues, mostly with cars that sit, and the alcohol separates from the gas. The straight alcohol will attack rubber seals in fuel pumps and lines. For this reason, it is not recommended for cars that are infrequently driven. Cars 25+ years old can also have issues, as the fuel system was never intended even for 10% ethanol use.
__________________
540 M-Sport package (Canadian market), factory Bluetooth phone integration, factory M-Audio 10" dual voice coil subs, Homelink, M5 rear stabilizer bar, M5 rear subframe braces, H&R 15mm wheel spacers, Bilstein B14 PSS coilovers, Stop Tech ss brake lines, Akebono Euro Ceramic brake pads, oem Brembo and Zimmerman rotors, Dinan Stage 1 software, Strong Strut front upper stress bar, BMP strut tower reinforcement kit, USA Spec Ipod/Iphone integration.
Reply With Quote
  #4  
Old 05-09-2017, 07:37 PM
Sephiroth Sephiroth is offline
Registered User
Location: Fayetteville, NC, USA
 
Join Date: Apr 2017
Posts: 80
Mein Auto: 2002 BMW 525i
Well the car has almost 112k on it now. Assuming ethanol was used the entire time it halved the life of the sensor. Again, not directly, but via blow-by and our stupid recirculation of crankcase vapors. I will be able to prove or disprove it this weekend. I intend on switching it with the other O2 sensor to see if the code follows. If it does, the sensor has failed. If it doesn't, I have some more digging to do. If the "good" sensor then trips and causes the code, it could be a wire rubbed through somewhere or a failed cat. If it doesn't come back I will be blown away. Simple test.

Anyway I am going to get some images of the sensor. If it is caked in phosphorous then we have our answer. If not, it just didn't last. I am just curious to know. Oh, and I don't want to blow $50~$60 a pop on sensors if the cat is bad!
__________________
2015 Ford F150 XLT 3.5 EcoBoost FX4 Off-Road
2002 BMW 525i
Reply With Quote
  #5  
Old 05-10-2017, 01:25 AM
Burning2nd's Avatar
Burning2nd Burning2nd is offline
Under the lift arms
Location: Under the lift arms
 
Join Date: Aug 2010
Posts: 7,985
Mein Auto: E39 540, E36 328is, E83x3
those are upstreem as well... B4 the cat
__________________
Specializing In BMW, Audi, Mercedes Benz ,Volkswagen, Volvo



15486372<-----
Reply With Quote
  #6  
Old 05-10-2017, 03:40 AM
Barracuz Barracuz is online now
Nothing to read here...
Location: Providence, R.I.
 
Join Date: Apr 2015
Posts: 1,624
Mein Auto: 2001 525i 5 spd
Youd burn the ethanol first so it's not fouling your o2s. What may foul your o2s is the oil seeping into the combustion chamber and all the byproducts of that fouling the o2s.

You could take an oil sample next oil change and send it to get analyzed. Then run zero ethanol and do a test on that oil.
__________________
The Crappitto-Stockitto-Baseito

**Word of Caution**
My knowledge is limited. Anything I write in my posts may or may not be accurate. To be honest I think its all crap.

Last edited by Barracuz; 05-10-2017 at 03:47 AM.
Reply With Quote
  #7  
Old 05-13-2017, 07:34 AM
Sephiroth Sephiroth is offline
Registered User
Location: Fayetteville, NC, USA
 
Join Date: Apr 2017
Posts: 80
Mein Auto: 2002 BMW 525i
All I run is gasoline in all my equipment. No gasohol (E10) in ANYTHING of mine. I run 93 octane, non-ethanol or 91 octane, non-ethanol.

I did not get a chance to work on the car yet. Been raining and we have a 90% chance today. Instead I am stealing BMWs, Ferraris, Lambos, and other nice cars in GTA5 on my PC. Close enough, and they only break down if the police shoot them up...
__________________
2015 Ford F150 XLT 3.5 EcoBoost FX4 Off-Road
2002 BMW 525i
Reply With Quote
Reply

See More Related BMW Stories


Forum Navigation
Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 5 Series > E39 (1997 - 2003)
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 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
© 2001-2015 performanceIX, Inc. All Rights Reserved .: guidelines .:. privacy .:. terms