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Unread 03-22-2008, 03:47 PM   #1
redhatman
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PO141, then PO138 ...

1998 ZJ Limited 4.0L

First I got the check engine light the day before our trip. I checked the codes today before work with our MasterTech reader, it said PO141 O2 sensor heater circuit malfunction (Bank 1, Sensor 2) So I cleared the code and disconnected the o2 sensor harness on the cat. Taped off the ends and went on my way. Drove probably 2 miles with a couple erands in between. All was well, then it popped on again. I quick hooked up the scan tool again, and it read:

PO138 O2 Sensor Circuit High Voltage (Bank 1, Sensor 2)

Any ideas? Isn't Bank 1 sensor 2 the o2 on the cat?


Leaving for a trip in an hour so please help asap. Anything to be concerned about? Thanks
-Pat

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5.9 ZJ 7" IRO, 35s, 8.8, hp30, locked, blah blah

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Those tires look freakin awesome Redhat... took the ZJ up a notch in my book. Now you're at notch 2.
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Unread 03-22-2008, 04:24 PM   #2
Jeeples
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Maybe I'm misunderstanding what you wrote, but it sounds like you still have the O2 sensor disconnected, right? When you start your vehicle, the O2 sensor will heat up quicker then the exhaust (this is the heater circuit) so that it can start reading the exhaust gasses sooner and adjust fuel trims to allow the engine to reach operating temperature in the correct amount of time.

If you've left this sensor unplugged after resetting the CEL, the heater circuit will stay on for longer then is allowed by the ECU, which will result in a CEL for the heater circuit on your O2 sensor. Until you replace the sensor, you will continue to have a CEL related to it.
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Unread 03-22-2008, 04:35 PM   #3
redhatman
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Ok, so would it be better to leave it unplugged or plug back in for the trip?
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-Pat

I am now a dealer for Iron Rock Off Road
I offer the same great products you already know about,
the same low prices you have been seeing, and with
the same experienced customer support, but I can offer it nearly 24/7

"Project Dirty Princess"
5.9 ZJ 7" IRO, 35s, 8.8, hp30, locked, blah blah

"Project Grow A Set"

Quote:
Originally Posted by CMARJEEP View Post
Those tires look freakin awesome Redhat... took the ZJ up a notch in my book. Now you're at notch 2.
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Unread 03-22-2008, 05:40 PM   #4
Windowsrookie
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I would replace it. I believe on 93-95 models it's just to tell you your cat is bad, but on 96+ it does control some engine stuff.
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Unread 03-22-2008, 09:02 PM   #5
zjay
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sensor 2 is the sensor either in or after the cat.

The voltage high code is just from the sensor being unplugged. Without the complete circuit, the pcm does not see the voltage going out being dropped by the sensor. Hence 'voltage high'. If it were shorted to ground, it would say 'voltage low'.
But to agree, ususlly just a sensor.
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Unread 03-23-2008, 12:40 PM   #6
redhatman
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Well I plugged it back in for the trip and it worked fine, engine light is still on but runs fine. So you are saying just replace the O2 sensor? I looked on RockAuto.com and they have one for $29.xx plus shipping.
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-Pat

I am now a dealer for Iron Rock Off Road
I offer the same great products you already know about,
the same low prices you have been seeing, and with
the same experienced customer support, but I can offer it nearly 24/7

"Project Dirty Princess"
5.9 ZJ 7" IRO, 35s, 8.8, hp30, locked, blah blah

"Project Grow A Set"

Quote:
Originally Posted by CMARJEEP View Post
Those tires look freakin awesome Redhat... took the ZJ up a notch in my book. Now you're at notch 2.
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Unread 03-23-2008, 12:50 PM   #7
a70eliminator
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Quote:
Originally Posted by Windowsrookie View Post
I would replace it. I believe on 93-95 models it's just to tell you your cat is bad, but on 96+ it does control some engine stuff.
I'm thinking not 93-95 o2 sensor is before the cat so it doesn't even know it's there. Good luck getting the old one out on your 96 unless it's been out before it could be a PITA, just replace both of them while your at it.
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Unread 03-26-2008, 07:13 PM   #8
redhatman
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Ordered a Bosch downstream for $52.xx and will install it tomorrow hopefully. I will update if works.
__________________
-Pat

I am now a dealer for Iron Rock Off Road
I offer the same great products you already know about,
the same low prices you have been seeing, and with
the same experienced customer support, but I can offer it nearly 24/7

"Project Dirty Princess"
5.9 ZJ 7" IRO, 35s, 8.8, hp30, locked, blah blah

"Project Grow A Set"

Quote:
Originally Posted by CMARJEEP View Post
Those tires look freakin awesome Redhat... took the ZJ up a notch in my book. Now you're at notch 2.
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Unread 03-31-2008, 06:36 PM   #9
redhatman
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Installed the Bosch, sucks. Still did not fix it. Has anyone ever successfully used a bosch? If you went with factory o2, how much can I expect to pay? Is there any way to bypass the sensor and have my engine light just stay off?
__________________
-Pat

I am now a dealer for Iron Rock Off Road
I offer the same great products you already know about,
the same low prices you have been seeing, and with
the same experienced customer support, but I can offer it nearly 24/7

"Project Dirty Princess"
5.9 ZJ 7" IRO, 35s, 8.8, hp30, locked, blah blah

"Project Grow A Set"

Quote:
Originally Posted by CMARJEEP View Post
Those tires look freakin awesome Redhat... took the ZJ up a notch in my book. Now you're at notch 2.
redhatman is offline   Reply With Quote
Unread 04-01-2008, 09:26 PM   #10
redhatman
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Installed the Mopar O2 Sensor now, cleared codes and still pops up. What else could I check?
__________________
-Pat

I am now a dealer for Iron Rock Off Road
I offer the same great products you already know about,
the same low prices you have been seeing, and with
the same experienced customer support, but I can offer it nearly 24/7

"Project Dirty Princess"
5.9 ZJ 7" IRO, 35s, 8.8, hp30, locked, blah blah

"Project Grow A Set"

Quote:
Originally Posted by CMARJEEP View Post
Those tires look freakin awesome Redhat... took the ZJ up a notch in my book. Now you're at notch 2.
redhatman is offline   Reply With Quote
Unread 04-01-2008, 10:01 PM   #11
WiLieR
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Sounds like it is time to get a schematic of the O2 circuit and start tracing the wires and testing for shorts in the circuit.
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Unread 04-01-2008, 10:15 PM   #12
redhatman
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yeah, I am afraid so...but I have no clue how to do any of that.
__________________
-Pat

I am now a dealer for Iron Rock Off Road
I offer the same great products you already know about,
the same low prices you have been seeing, and with
the same experienced customer support, but I can offer it nearly 24/7

"Project Dirty Princess"
5.9 ZJ 7" IRO, 35s, 8.8, hp30, locked, blah blah

"Project Grow A Set"

Quote:
Originally Posted by CMARJEEP View Post
Those tires look freakin awesome Redhat... took the ZJ up a notch in my book. Now you're at notch 2.
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Unread 06-20-2008, 07:25 PM   #13
Carllo
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Request Code

Hi all,

Can I request the codes ODB in the panel of my JGCLaredo 98/98? I try that cycles of "on/off" 3 times, 5 times, "n" times and nothing hapens . I try several times with several ways, and nothing.
It's impossible ? Only it's possible in the 1997 or below?

I know that in the XJ simple push the "zero hodometer" when "on" the panel and the selftests hapens....



Thanks......
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Unread 06-20-2008, 09:18 PM   #14
rm2001wj
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It's possible for 93-97 and for 99-04, but not 98. It takes a code reader for that year.
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Unread 06-21-2008, 10:13 AM   #15
Carllo
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Quote:
Originally Posted by rm2001wj View Post
It's possible for 93-97 and for 99-04, but not 98. It takes a code reader for that year.
Thanks rm2001wj
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