To say it another way, do O2 sensors degrade and affect performance? Or do they work all the same until the point of failure?

Or

Does changing them before failure help in any way, or just help avoid a future untimely repair project?

 

It is said that Oxygen Sensors are only good for approximately 150,000 miles. I have no proof.


However, old sensors have a tendency to degrade fuel economy.


Sensors should be changed as a set, i.e., upstream and down stream together.


Use only NTK sensors. The Jeep 4.0 came from the factory with NTK sensors. Other sensors, such as Bosch sensors, don't seem to work well in our Jeeps.

 

I had 2 NTK sensors bad right out of the box. Took time and money to figure it out, as they were the last things I suspected. NTK would not give any labor allowance even though I had to pay to have them removed and replacements installed. 2006 3.7 Grand Cherokee, 146K miles. I did have all 4 replaced at the same time on that one.

I have never had trouble out of Bosch. Last week I replaced a sensor in a 3.7L 2005 Liberty. Bosch came out, Bosch went back in. Bank one, sensor two. 177K miles on vehicle. Light went off instantly upon restart. Just replaced the faulty one.

 

Interesting comments on brands. I will look more into this.
I am thinking of changing the ones on this 96 XJ. 247K and unknown replacement history.

Just changed all four on my Dakota 4.7 2002. Similar setup with the mini-cats as the Calif emissions 2000-2001 XJ. However a bit more PITA to get to the upper ones. Installed Denso brand. Any comments on that brand installed on XJ's? Dakota forum folks are quite unified in opinion that those are the best for the 4.7. Happy so far with them. Sensors had heater circuits burned out and were throwing the codes. No codes now after Denso brand install.

Rock Auto had them for about $23 each. Same item locally is about $60. Don't know what they want for the non-heated 96 XJ ones.

 

I had a part throttle hesitation that was fixed by replacing an O2 sensor that got lazy. I watched the O2 signal on an analog volt meter and it was a little bit slow. It was either that or the new vacuum harness that fixed it. (I replaced both at the same time.. No free time to do one at a time.)

 

I bought an '00 XJ about 2 years ago. Cheap. Running but not really drive-able. Been fixing it. Got her on the road pretty quick then started fixing all the little things. I swapped out all my O2 sensors just because. No check engine lights just figured with 150K they needed to go. Plus my gas mileage so so. Used NTK's because that is supposedly factory and there are many posts about not using other brands. Want to say that I have seen an improvement in MPG. But I also bought brand new Cooper Discovery HT's in a 225 75 15. Swapped my front and rear diff fluids for synthetic, and upgraded to 4 hole injectors. Also taking it easy on the skinny peddle. Jeep is stock by the way except for the injectors.

 

Please elaborate on 4 hole injectors.

Thanks
goodyoleboy

 

there's compatible injectors with 4 holes, that improve fuel atomization. Even up to 12 holes. There's plenty of info on thus, just search and read up.

 

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