NAXJA Forums -::- North American XJ Association  

Go Back   NAXJA Forums -::- North American XJ Association > NAXJA Unibody Jeep Technical Forums > Jeep Cherokee XJ (1984 - 2001) > OEM Tech Discussion
HOME Member FAQ Sponsor Info Rules Bylaws E-Mail

OEM Tech Discussion Forum for OEM (Original Equipment) or stock XJs and MJs.

Reply
 
Thread Tools Display Modes
  #1  
Old March 11th, 2020, 09:51
gdufour11 gdufour11 is offline
NAXJA Forum User
 
Join Date: Mar 2020
Location: Portland, OR, USA
Posts: 3
Downstream O2 Sensor Help

ownstream O2 Sensor Help!

All,

I cannot pass the DEQ emissions test because I cannot seem to keep my O2 sensor working for more than 1 day. I have replaced my O2 sensor, twice now and get the same results. I get a P0138 code. I have a 2000 Jeep Cherokee Classic 4WD, XJ.

Initially, after replacing the sensor, everything is running fine, I get a reading of 0.4-0.42 V from the Bank 1 Sensor 2, then all of the sudden it will start reading 1V and then throws the code. It seems like then sensor works for a couple of hours of running then just gets cooked! The last one I used was a Bosch sensor. I don't know what else, the wiring seems fine and I would assume is good because I get a decent reading for a while before it fails.

Is it possible my PCM is just bad?

I hate to dump a bunch of money into this thing, just want to keep it going for a few more years!
Reply With Quote
  #2  
Old March 11th, 2020, 09:54
RCP Phx RCP Phx is offline
NAXJA Forum User
 
Join Date: Mar 2003
Location: Phoenix,Az
Posts: 13,502
Re: Downstream O2 Sensor Help

The first thing I would look at is the wiring and it's a special twisted pair.
Reply With Quote
  #3  
Old March 11th, 2020, 10:02
Saudade's Avatar
Saudade Saudade is offline
NAXJA Member
 
Join Date: May 2005
Location: SoCal
Posts: 2,228
Re: Downstream O2 Sensor Help

Yeah, check the harness and make sure it's not rubbed through somewhere.

Any running issues? Do you have any freeze frame data?
__________________
1988 Laredo 2wd Auto, AKA "Grey Ghost", 206K
Reply With Quote
  #4  
Old March 11th, 2020, 10:14
Tim_MN's Avatar
Tim_MN Tim_MN is offline
Freakish Hand Strength
 
Join Date: Mar 2003
Location: Minneapolis, MN
Posts: 6,959
Re: Downstream O2 Sensor Help

Wiring issues are much more common and much more likely than PCM issues.


P0138 JEEP - O2 Sensor 1/2 Circuit High

P0138 JEEP Possible Causes
•Faulty Rear Heated Oxygen Sensor Bank 1
•Rear Heated Oxygen Sensor Bank 1 harness is open or shorted
•Rear Heated Oxygen Sensor Bank 1 circuit poor electrical connection
•Intake air leaks
•Exhaust gas leaks
__________________
.
.

Quote:
Originally Posted by bimmerjeeper

Go ahead and slam the liftgate down on a blanket, and see how long you are laughing.

Last edited by Tim_MN; March 11th, 2020 at 10:18.
Reply With Quote
  #5  
Old March 11th, 2020, 10:23
gdufour11 gdufour11 is offline
NAXJA Forum User
 
Join Date: Mar 2020
Location: Portland, OR, USA
Posts: 3
Downstream O2 Sensor Help


What should I be reading voltage wise from the vehicle across the heater terminals? What about the O2 sensor?


Sent from my iPhone using Tapatalk
Reply With Quote
  #6  
Old March 11th, 2020, 10:25
gdufour11 gdufour11 is offline
NAXJA Forum User
 
Join Date: Mar 2020
Location: Portland, OR, USA
Posts: 3
Downstream O2 Sensor Help

This screen shot is from this morning.



Last night it was reading .4 V on o2 bank1 sensor 2


Sent from my iPhone using Tapatalk
Reply With Quote
  #7  
Old March 11th, 2020, 15:47
emx721 emx721 is offline
NAXJA Forum User
 
Join Date: Jan 2017
Location: wisconsin
Posts: 42
Re: Downstream O2 Sensor Help

I had almost the exact same issue, I can almost guarantee the wiring got destroyed by the drive shaft. Follow the harness wiring and you'll see the wires got rubbed out and is sitting on the driveshaft. I put them together with wire butt connectors and all is good now.
Reply With Quote
  #8  
Old March 13th, 2020, 10:22
lawsoncl lawsoncl is offline
NAXJA Forum User
 
Join Date: Jan 2006
Location: North Idaho
Posts: 5,223
Re: Downstream O2 Sensor Help

Quote:
Originally Posted by gdufour11 View Post
What should I be reading voltage wise from the vehicle across the heater terminals?

Pretty sure it's 12-volts to the heater
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
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

Similar Threads
Thread Thread Starter Forum Replies Last Post
Downstream O2 sensor iluv83vettes OEM Tech Discussion 4 February 4th, 2015 05:34
Downstream 02 Sensor wiring Slimgoaty OEM Tech Discussion 4 January 5th, 2012 11:31
Downstream O2 sensor needed? blacklabel000 OEM Tech Discussion 22 October 26th, 2010 21:48
Downstream O2 Sensor? Redsnake OEM Tech Discussion 3 September 3rd, 2008 09:29
Downstream o2 sensor jwtrapper OEM Tech Discussion 1 February 23rd, 2007 12:19


All times are GMT -7. The time now is 18:54.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
NAXJA and NAXJA logo's Copyright NAXJA. All content/images Copyright NAXJA 1999-2014