BMW E46 throwing and clearing P0161 code

[billschusteriv]

A few months ago, the wife was driving the wagon and the Service Engine Soon light came on. No issues with drivability, no other symptoms - and the code cleared before I got home to check it. I drove it for a while and didn't think anything of it.

Flash forward to last week... and the service engine soon light comes back on. No drivability issues... other than a slight drop in fuel economy... so I head over to my indy mechanic's house to have him read the codes for me (he usually does it for free - I need to get a reader). The code cleared when I started my car just before leaving for my mechanic. But he was able to pull the code - it came up as:

P0161 - O2 Sensor Heater Circuit Malfunction

After looking through the Bentley manual... I found that it is... more completely:

P0161 O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 2) - or the Post Cat O2 sensor coming off cylinders 4-6.

Also listed here: http://forum.e46fanatics.com/showthread.php?t=303141

Considering that the code cleared, we're holding off on replacing the sensor for now. I probably should replace at my earliest convenience.

Since no other codes came up during the scan - I'm thinking the original SES light was related.

Anything I might have missed or overlooked?

[kayger12]

No, I think the post cat o2 sensor was/is your issue.

Some more info here. (http://www.obd-codes.com/p0161)

[billschusteriv]

UPDATE

So everything has been relatively quiet with this the post cat O2 sensor until now. And since we're getting ready for the drive to the meet next week, I figured it is a good time to replace it since I didn't do this sooner.

Popped the Service Engine Soon light yesterday morning on the way to work. Stopped and picked up a Actron AutoScanner Plus CP9580
code reader (http://www.zhpmafia.com/forums/showthread.php?1735-What-did-you-buy-today&p=65204#post65204) yesterday at Advance Autoparts. After getting home last night, I checked the codes and found the P0161 code, as expected, along with a P0172 System too Rich (Bank 1).

I'm going to pick up the O2 sensors here momentarily...

[danewilson77]

Roger...check Amazon.

[billschusteriv]

Good info Dane. I did a search for your earlier post where you said you got your sensors on Amazon (link to sensors below).

Just got off the phone with my indy mechanic. He suggested before I buy all four sensors, that I do some stuff first.


First, write down and clear the codes.
Then, since I have the functionality, he recommended using my code reader to watch the live data on my O2 Sensor. He said to watch for patterns on the voltages. If a sensor is truly bad, the voltages on one should not be behaving like the others (not changing or highly erratic).
Finally, I recently changed gas in the car. He suggested that the changes in gas (good/bad) that I am buying may have caused the code to pop. He said to buy a few tanks of good gas, drive about a hundred miles, and check the code reader to see if there are any "pending" codes. He indicated that if an O2 sensor is really bad - the codes should come back fairly quick.


I like this approach for the troubleshooting aspect but worry about delaying the maintenance. Worst comes to worst... my fuel economy goes down the drain when the sensor does fail until I can get it replaced.

[danewilson77]

Also remember the Shark permanently cleared my codes.

[billschusteriv]

I have a 2002 325 XiT so... from realoem.com, these are the oxygen sensors I need:

http://www.realoem.com/bmw/diagrams/f/a/30.png

Pre-cat : 01 REGULATING LAMBDA PROBE, L=320MM, qty 2, p/n 11781742050, $215.65 ---> Bosch p/n 13477
Post-cat: 02 Lambda Monitor sensor, L=990MM, qty 2, p/n 11781433940, $215.65 ---> Bosch p/n 15109

Amazon has the best price for the Bosch 15109 post-cat O2 sensors at $53.66 with free shipping. (http://www.amazon.com/gp/product/B000BZI3GW/ref=as_li_ss_tl?ie=UTF8&tag=zhpcom-20&linkCode=as2&camp=217153&creative=399349&creativeASIN=B000BZI3GW)

FCPGroton, BavAuto, and Pelican parts follow on at $68, $69, and $85, respectively.

getbmwparts.com has the worst price for these sensors at $208.86 for 2 ($104.43 each) with about $14.00 ground shipping.

[billschusteriv]

Also remember the Shark permanently cleared my codes.

Permenantly?

You mean the software upgrade from the Shark fixed the glitch Linh and some other people were having (http://www.zhpmafia.com/forums/showthread.php?860-Hey-Dane!-Do-these-codes-look-familiar&p=19107#post19107)?

That might be another good step... I probably haven't had the software upgrade....

[danewilson77]

Amazon has the best price for the Bosch 15109 post-cat O2 sensors at $53.66 with free shipping. (http://www.amazon.com/gp/product/B000BZI3GW/ref=as_li_ss_tl?ie=UTF8&tag=zhpcom-20&linkCode=as2&camp=217153&creative=399349&creativeASIN=B000BZI3GW)

FCPGroton, BavAuto, and Pelican parts follow on at $68, $69, and $85, respectively.

getbmwparts.com has the worst price for these sensors at $208.86 with about $14.00 ground shipping.

Bill....see if the ones I got from Amazon will work for your car. If so...they're yours for cheap.

Droid + Tapatalk = FTW!

[billschusteriv]

Bill....see if the ones I got from Amazon will work for your car. If so...they're yours for cheap.

Droid + Tapatalk = FTW!

Thanks Dane! I was just posting up my part number when you replied... looks like you posted that your sensors are p/ns 11787523434 and 11787523435 (Bosch 17215 and 17216).


I have a 2002 325 XiT so... from realoem.com, these are the oxygen sensors I need:

http://www.realoem.com/bmw/diagrams/f/a/30.png

Pre-cat : 01 REGULATING LAMBDA PROBE, L=320MM, qty 2, p/n 11781742050, $215.65 ---> Bosch p/n 13477
Post-cat: 02 Lambda Monitor sensor, L=990MM, qty 2, p/n 11781433940, $215.65 ---> Bosch p/n 15109


It looks like the part numbers are different for the 325i and the 330i and/or ZHP.

Bummer.

I will take a look and see if they are compatible/interchangable.

You aren't planning on hanging onto them for a future PM?

[danewilson77]

I would rather have cash for other stuff. It would help me...and help you...if they would work.

No worries though if you are uncomfortable with it, or find out they won't work.

[billschusteriv]

Cool. I will check.