Should I replace my O2 sensors?

[Jeff7]

Hey guys, title says it, should I replace my O2 sensors? My truck is a 98 with the 5.7L and has 350k km (217k miles) and I think the sensors may be original. If not then they would have be replace a long time ago before 200 km. There's nothing wrong the way the truck runs but I'm thinking just as maintenance? I replaced my spark plugs, wires, distributor cap and rotor last summer and noticed that the truck ran much better, even though there was nothing actually wrong with it beforehand, thinking this might be the same case? Is there anything else like this that I should be concerning myself with? Thanks.

 

[Black_cirrus]

I wouldn't unless something seems amiss or you've had coolant get in the exhaust, I've seen plenty of threads pulled and had the pipe break off on my own truck. I've never seen a huge increase unless there was an abnormal condition to start with.

 

[kennythewelder]

If your sensors are faulty and need to be replced, you will get a CEL. As long as they are working properly there is no need to replace them. Also, when replacing the 02 sensors, it is important to replace all 4 of them. They all need to be in sink with each other. The two front sensors adjust fuel trim ratios, and the two rear sensors let the ECM know that the cats are working, by comparing the data to what the two front 02 sensors are reading. The ECM is doing all the work. The 02 sensors are just sending a signal to the ECM for processing.

 

[Jeff7]

Ya I figured I should replace all 4 together, but thanks for the confirmation.

I've also heard the threads can strip, I figured I would try to back out my current gently and see how it went before buying new ones, if they were too tight I would just leave them.

So you guys don't think that they could still be working well enough to not cause an engine but still not working they best they could, causing my engine to not run as well as it could?

 

[beardeddummy]

It's really hard to tell unless you do it I wouldn't worry much about the rear 02s because they only tell the computer if a cat is there and working. the fronts couldn't hurt but save the ones you have now for hard times. if you're going to do it get some Pb blaster and hose down good and let it sit over night. if they have been replaced hopefully someone used antiseize if pb blaster will be wasted but you'll thank yourself for doing it if not

 

[superdave]

At that age, I wouldn't touch them unless they were causing a problem. I would imagine that if they were original, they are now heat/rust welded to the exhaust. I replaced the fronts on mine a few months ago, only because I put on tri-y headers and that would be the time to do it. The rears are still original and have caused no problem. They just check cat efficiency and have nothing to do with fuel trim.

 

[jkeaton]

I replaced mine just for the heck of it when I did my last tune up at 201,000 miles. It was like $15. Didn't make any difference but at least I know it's new now.

 

[beardeddummy]

It's nice to see I'm not the only one up this early

 

[jkeaton]

It's nice to see I'm not the only one up this early

Had to get up early to keep my buzz. Baileys and coffee. Almost drunk already. Oops. Wrong thread.

 

[beardeddummy]

Had to get up early to keep my buzz. Baileys and coffee. Almost drunk already. Oops. Wrong thread.

Best hangover ever never sober up.
I'm in the woods right it's finally cooling off in Arkansas