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O2 sensor? If so how do I change it.

S

sleestack

NAXJA Forum User
Location
New York
I installed a dynomax superturbo catback today, as soon as I turned the jeep on I got a check engine light.

I ran the codes and got a 0137 and 0138, being a O2 problem. I was wanting to change the O2 sensor out because I get a consistant 9.26 miles per gallon.

How do I change the o2 sensor, I believe it is on the exhaust manifold but do I have to gain access from under the jeep? How hard is it to change?

Just for reference this is a 1996 4x4 sport 4.0 auto.
 
You'll need a 7/8" box wrench and some decent upper arm strength.

Crawl underneath and look at the exhaust pipe right below the exhaust manifold, near the front driveshaft. Crank on it till it comes loose (might need pb-blaster and you'll definitely want to use the closed end of the box wrench to avoid rounding it off.)

Worst one I ever did was on my 91, took me about 45 minutes due to being seized in place from 19 years of heat and road salt.
 
On a 96 yeah. There is one downstream of the catalytic converter but all it does really is monitor whether the catalytic is working properly.
 
Inspect the wiring to both O2's. Being exposed it gets damaged easy.

Bosch is best usually.

Do some search- 9 mpg can be a leaky exhaust manifold. gasket or manifold itself.
That leak wipes out the fuel mpg by giving a false reading from the O2 and 'puter trying to compensate.
 
Last edited:
Definitely use some penetrating oil on there. They will usually break loose easier when hot.

When you are sure you are not going to reuse the sensor just cut the wires to get the box end wrench on it. If you are planning to reuse it then you should buy a sensor socket.
 
joe_peters said:
Definitely use some penetrating oil on there. They will usually break loose easier when hot.

When you are sure you are not going to reuse the sensor just cut the wires to get the box end wrench on it. If you are planning to reuse it then you should buy a sensor socket.
Click to expand...

x2 if you cant break it free hot, Ive been known to smash the whole top off and just use a regular socket.
 
recently changed my o2 sensor on 99 cherokee. no pb blaster and used an open end of a 7/8" wrench. came right out. was a little warm though. its easily accessed from the underside of your jeep. best of luck
 
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