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Check engine light, error code P0138


 
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scratch.jay
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Joined: 29 Apr 2010

PostPosted: Thu Apr 29, 2010 5:57 am    Post subject: Check engine light, error code P0138 Reply with quote

Hi there,

I have a 1999 jeep cherokee. This check engine light just came on yesterday. The error code is P0138 scanned at autozone.

A post here says
138 O2 Sensor Circuit High Voltage (Bank 1 Sensor 2)
What does this mean? Where should I start to poke?

I am new for car. Like to do a little research before doing something to screw it up. Thanks. Razz
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Orangeamc13
Got Rev Limiter?
Got Rev Limiter?


Joined: 20 Feb 2006
Location: East Springfield, Massachusetts - U.S.A.

PostPosted: Thu Apr 29, 2010 7:50 am    Post subject: Reply with quote

Replace the "down-stream" Oxygen Sensor, after the catalytic convertor.
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scratch.jay
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Joined: 29 Apr 2010

PostPosted: Fri Apr 30, 2010 6:47 am    Post subject: Reply with quote

A question about the check engine light. Do I have to erase the error code by a OBD scanner after I put on a new O2 sensor? Or the check engine light will go away by itself right after it goes back to normal? After some reading I got an impression that even after replacement the check engine light will sustain. That confused me.

Is there a chance that it is caused by some loose wires or bad fuse?
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Orangeamc13
Got Rev Limiter?
Got Rev Limiter?


Joined: 20 Feb 2006
Location: East Springfield, Massachusetts - U.S.A.

PostPosted: Fri Apr 30, 2010 8:51 am    Post subject: Reply with quote

The light should go off, if you fix the problem, but the code will be stored in the computer. I would erase the code with a scanner, but you don't have to. It's better to start with a clean slate, that way if the cel comes on again, there's no confusion.

It is possible that a fuse is causing this code, but unlikely. Check the fuses and also check the o2 sensor wiring for signs of cracks or burns.

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scratch.jay
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Joined: 29 Apr 2010

PostPosted: Fri Apr 30, 2010 10:20 am    Post subject: Reply with quote

I scrawled underneath my car, and located the O2 sensor.
Should be ok for me to replace it.
BTW wires look good.

Here is a stupid question.
Where is the fuse for O2 sensor?
I looked it up in my manual and some web.
But can't find it.

Does cherokee have one? Very Happy

Thanks.
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Orangeamc13
Got Rev Limiter?
Got Rev Limiter?


Joined: 20 Feb 2006
Location: East Springfield, Massachusetts - U.S.A.

PostPosted: Fri Apr 30, 2010 2:16 pm    Post subject: Reply with quote

There's two fuse locations. One is under the hood on the pass. fender area. It's a black rectangular box. The other is behind the pass. kick panel, under the dash, near the door. I'm not sure which fuses are for the heater circuit. Check them all and replace any that are blown, with the proper color or amp.
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scratch.jay
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Joined: 29 Apr 2010

PostPosted: Sat May 01, 2010 10:16 am    Post subject: Reply with quote

Last night I put a new O2 sensor on it. However the check engine light was still on after driving it around for a while last night and this morning. Then finally find a guy help me erase the code. Now it went off.

One thing I didn't get a chance to try is to erase the code before put on a new sensor. Might be something intermittent and not worth a new sensor. Do you usually do this at the first step? Rolling Eyes

Thanks. Very Happy
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