Is it worth replacing them? Would I gain some MPG? I have a $50 credit that I need to use on $100+ purchase by Jan 19. Thought it might not be a bad idea to save a few bucks at the pump.

 

I just replaced mine in my XJ. So far my MPG's have been going up, but I also changed the fuel filter, added some fuel stabilizer, changed the oil/filter, etc. I can say it wasn't too fun to replace under my XJ, but then again mine is stock height. Mine cost me $54 @ Napa.

 

The O2 sensor is really the only thing that directly affects MPG of what you replaced.

 

Anyone else have experience with new O2s?

 

What do you need to know?

 

Is it worth replacing them? Will mpg increase? I'm assimg they are original. Since the jeep oaths winter DD better mpg would be good. I have two $50 off coupons on $100 purchases and I'm tryin to use them as wisely as possible.

 

Uh yeah. The computer uses them to set fuel to air ratio after it's warmed up. They're specced for around 60k or 80k mile lifetime.

 

so I guess at 160k they are well used?

 

How old is your cat? Have smog results been good? If you know your cat is starting to go, that O2 sensor won't last as long, along with your egr valve.

 

Yes, O2 sensors are quite important. NTK is the OE supplier. They work in conjunction with your cat. ,other emissions, and with the the computer. I have had two other Jeep. I usually change them at around 100k or when the CEL comes on. They can most certainly affect your MPG's.

 

Oops. Meant to say Jeeps.

 

Replace them. Both of them. The average lifespan of the OEM oxygen sensors on your vintage 4.0 is between 100k and 150k, depending on engine efficiency.

I highly recommend you purchase NTK sensors; they would be the exact same sensors as the ones currently installed on your engine.

 

Cat is original to my knowledge. I havent had any issues with it.

Thanks for the input guys. Now to clarify I need the two upstream O2 correct? To my knowledge those are the ones that affect MPG, the downstream, after cat O2s just make sure the cat is working correct?

 

What year is your Cherokee?

 

You should replace all 4 to do the job right.