If Bank 1 need to be replaced, do I need to replace both? I see mix opinion on this and at times all 4. Suggestions please.

 

Replace banks together. All four isn't necessary.

 

I thought you replace the upstream together. That is how I understood recommendation, but I may be wrong.

 

I believe you're right. I bought all 4 and thinking I dont need the replace the back since they are not throwing any codes anyway. Thank you

 

A long-time, vocal contributor to this forum, now long gone, always said to replace all four together. I've never understand that. If the rears are not throwing codes then why bother? The rears (downstream) measure only how well the cats are performing and have absolutely no impact on engine management.

As for replacing the fronts in pairs, I've seen some suggestions that somehow the left and right banks will be "imbalanced" if you don't replace them together. That too makes no sense to me. I'm not saying that I am 100% certain I am correct; I have just never seen what I believed to be credible arguments to replace them in pairs, nor have I seen any reporting results of problems arising because only one O2 sensor was replaced.

I nonetheless once tried to replace the upstream pair together when a problem was indicated with only one upstream O2. It turned out that one of the two Bosch 15175 sensors I bought was bad out of the box, so I reinstalled the "good" sensor I'd removed. The truck ran great like that for a very, very long time. By "ran great" I mean that I could see the short-term and long-term fuel trims cycling in their normal ranges as displayed on my UltraGauge.

That does, however, illustrate why although you can save a few bucks ordering your O2 sensors online in my opinion it's better to buy them locally so that you have an easier and more immediate ability to return any that are bad out of the box, which seems to be an all too common occurrence.

There is nothing wrong with replacing in pairs; it just doesn't seem necessary.

 

I tend to agree with min01. I listen to and respect the long time, vocal members and end up doing what I think is right. In my opinion, even lifers can be doing it either wrong all along or doing unnecessary replacements. I replaced the upstream O2's because they both were staying at a certain voltage, and never changing. Now both of them are cycling like the should.
On another subject, I will never agree with anyone that says 210-220 degrees is ok with these all aluminum engines. The Rover engine failures, i.e. liners, head gaskets are caused by heat more than anything else.
Just my .02

 

For the cost, do all four. If some are dead all the rest are close to end of life. You get a boost in milage, so pays for itself.
Would be an easy job if you could get at them, but be prepared for working with 2º of sweep and a lot of tools jammed up into the guts of your rig. Driver's front was the hardest if I remember correctly. Get the tool!

 

I totaly understand your opinions since now, its throwing me 0134, 0135 and 0155 all related to the pervious side that was the problem. I might have to use the good one which i just removed coz it was working fine in the beginning. Now if this new replacement is broken, then have to send it back online. Anyway, the same sensor online is more than half the price than locally purchased. The hassle part is that it will take days again to have this replaced. This is the first time i replaced a sensor and it was easy. Ill check my connections before sending thus back since the right side was a bit greasy. Contacts might be weak. Ill keep you informed with the progress if my 1st fix worked. Thanks guys.!

 

I replaced my front two individually. One about 2 years ago, and the other a couple weeks ago when that one went out. I thought they were extremely easy to replace. The driver side was a bit hard to get reconnected, but the passenger side can be done right from the engine compartment without even getting underneath.

 

Also, the first one I bought at Autozone and is Bosch, the newer one is an aftermarket one I got for $20 off ebay.