Welcome to the North American Subaru Impreza Owners Club Wednesday October 22, 2014
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC Technical > Factory 2.5L Turbo Powertrain (EJ Series Factory 2.5L Turbo)

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads.
Reply
 
Thread Tools Display Modes
Old 12-22-2012, 01:12 PM   #1
Darth Sleader
Scooby Newbie
 
Member#: 293322
Join Date: Sep 2011
Vehicle:
2008 WRX Sedan
Dark Gray Metallic

Default P0031 O2 Sensor issues SOLVED

Hello,

It's been over a year that I've been dealing with this and it seems that it's finally fixed! I really hope this helps someone else. This would have saved me some serious time and money.

I've gone through five (!) O2 sensors in a year. Each time, the code was P0031 which deals with the electronic heater in the sensor that gets it up to operating temps faster for more accurate O2 readings.

The bottom line is, the issue for me was in my headers. I have a Perrin equal length header, the older one with the slip-joint adjustable fittings. Newer models do not have the issue that caused me so much strife.

The issue is that the sensor bung is welded into the header in such a way that the sensor sits exactly parallel to the ground. As the gases in the exhaust stream cool, moisture forms and collects on surfaces inside. This moisture gets in the tip of the O2 sensor and eventually kills it. The factory Subaru header has the sensor situated so that it points downward at a slight angle (maybe 15 deg or so.) Apparently this downward angle allows moisture to exit the sensor tip.

Last week my mechanic took the header off and took it to an exhaust welder to reposition the sensor bung. As it turns out, the bung is welded right at the junction between right and left piston banks, and repositioning it "northward" to point down would only be getting exhaust from 2 pistons, not all 4. So he decided to mount the sensor in the uppipe instead. It's approx. 3" farther downstream than the original position. He did extensive testing and readings on sensor data and it seems to be rock-solid. Well within spec.

My mechanic mentioned some other cars he knew of that had this same problem and same symptoms as well so I'm pretty confident this will be a fix.

Good luck!

Jer
* Registered users of the site do not see these ads.
Darth Sleader is offline   Reply With Quote
Old 01-02-2013, 10:20 PM   #2
250SilverSti
Scooby Newbie
 
Member#: 306017
Join Date: Jan 2012
Chapter/Region: VIC
Location: Victoria, B.C
Vehicle:
2004 WRX STi
Silver

Default

Thank you so much. I really hope you are right. Im gonna do you did and see if that works. What downpipe are you running on your car. I really appreciate all this information. It sounds like what my car has been doing . Look for update soon
250SilverSti is offline   Reply With Quote
Old 01-03-2013, 10:21 AM   #3
Darth Sleader
Scooby Newbie
 
Member#: 293322
Join Date: Sep 2011
Vehicle:
2008 WRX Sedan
Dark Gray Metallic

Default

Quote:
Originally Posted by 250SilverSti View Post
Thank you so much. I really hope you are right. Im gonna do you did and see if that works. What downpipe are you running on your car. I really appreciate all this information. It sounds like what my car has been doing . Look for update soon
Hey!

My downpipe is a Perrin (I have their turboback exhaust setup). The O2 sensor was inserted into the UPpipe, which is also a Perrin.

I hope that helps!

Jer
Darth Sleader is offline   Reply With Quote
Reply

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 Off
Forum Jump


All times are GMT -4. The time now is 06:11 AM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2014 Axivo Inc.
Copyright ©1999 - 2014, North American Subaru Impreza Owners Club, Inc.