Welcome to the North American Subaru Impreza Owners Club Tuesday October 23, 2018
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
Go Back   NASIOC > NASIOC Technical > Electrical & Lighting

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. 
Thread Tools Display Modes
Old 12-07-2017, 01:46 PM   #1
Scooby Newbie
Member#: 478765
Join Date: Dec 2017
Location: MA
2007 Impreza wagon

Default Voltage at upstream o2 sensor conection?

07 Impreza Wagon, 130k Miles

Chasing down a p0031. Heated circuit on bank 1 sensor 1 faulty/low voltage. I checked all the fuses in the engine bay, and all are in tact. The next thing I wanted to check before swapping with new sensor is the voltage at the connector to ensure there isnít a wiring problem elsewhere. Iím new to this so Iím not sure if I tested it correctly, but I removed the sensor from the connector, put the car in start (not running) and checked the voltage at each prong in the connector (4 wire connector). I got a 12v, a 0, 2.4 and 2.8 volts. Iím not sure what a proper reading should be and Iíve been scouring the internet for days. Any help would be appreciated.
* Registered users of the site do not see these ads.
Greasyjonny is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 12-11-2017, 02:32 PM   #2
Scooby Newbie
Member#: 477892
Join Date: Nov 2017
Chapter/Region: NESIC
Location: Waterbury Center, Vermont
2000 Impreza Wagon


12 volts is good, that means your harness is getting power from the ecu for the supply to the heater portion of the sensor (grey wire). There should be 0 volts @ the connector for the ground to the heater portion of the sensor (one of the white wires). One of the other two (2.4v and 2.8v) readings you got was the (+) supply to the air/fuel circuit and the other reading is a wire that is the ground for the air/fuel circuit portion of the sensor. The heater circuit uses the two white wires, the air/fuel a grey and a black.

I think your good, heater circuits in H02s tend to go bad after not all that long. They are fragile and are exposed to alot of abuse by high heat, moisture and vibration.
IanT-EJ22 is offline   Reply With Quote

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 12:49 AM.

Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2018 Axivo Inc.
Copyright ©1999 - 2017, North American Subaru Impreza Owners Club, Inc.