P0138 annoying code

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Jun 30, 2010 | 12:39 PM

ca441970

Thread Starter

Member

Joined: Jun 2010

Posts: 155

Likes: 1

From: Easthampton, MA

Year: 1999

Model: Cherokee

Engine: 4.0

P0138 annoying code

Ok, I had the P0138 code, comes and goes. I reset it. It came back, P0138 is for the o2 sensor. I replaced my upstream sensor. Came home a bit ago, CEL on again, P0138. WTF? Is it an error code, just popping up for ha ha's? OR do I need a downstream sensor? I looked it up and it also says possible 12v power short. P0138 is o2 sensor over volts? Any info would be great.

Mar 18, 2011 | 11:15 PM

J20jeepster

Junior Member

Joined: Mar 2011

Posts: 54

Likes: 0

From: Oregon

Year: 96

Model: Cherokee

Engine: 4.0

That code is for the O2 after the cat.

Mar 18, 2011 | 11:23 PM

SeriousOffroad

CF Veteran

Joined: Apr 2008

Posts: 13,952

Likes: 17

Model: Cherokee

Did you check the fuse in the junction panel?

Mar 19, 2011 | 12:24 PM

PanteraRosa

Junior Member

Joined: Mar 2011

Posts: 45

Likes: 0

From: backwoods preacher boy mountain hut

Year: 1996

Model: Cherokee

Engine: 4.0 IL6

Yah, this happened to me, it would throw the code randomly, over a few months. I just replaced the downstream o2 yesterday and it hasn't thrown it just yet...but yeah, check your fuses first.