Change all oxygen sensors or not?

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DR1

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I have a 2000 F150 4.6 V8 with 112k miles on it. Runs great to me overall.
Should I only change all 4 of my 02 oxygen sensors now,or wait until it throws up some code on my dashboard?
 
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I would wait til it either throws a code or you have to replace the manifold(s) for cracks or broken studs. Don't change the rear unless they are throwing codes, a lazy but functional rear O2 is less likely to trip a P420/430 code
 
How is the fuel mileage? I have never changed rear ones, i have picked up mpg with front 02 sensors on high mileage engines. If your fuel mileage had not dropped noticably, i'd let them be.
 
Originally Posted By: dlundblad
I am all for PM, but don't fix what isn't broke.


This!
thumbsup2.gif
 
I had an 02 F150 and after I changed out all 4 sensors, the truck idled a LOT smoother.
 
If I decide to change all 4,should I stick with motorcraft or use another brand name?
 
Work was necessary on the forward end of a friend's F-150 exhaust system.
He's still reminiscing over how the immovability of the working sensors resulted in the most severe manifold+pipe repair ever done by man.
Haven't seen it myself.
 
I never replace working parts. I just remove and wash with a solvent anything that is exposed to build up of crud. I "inspect" my O2s once in a blue moon, just so that they don't "rust-weld" themselves. My Heep needs that kind of attention, other cars' pipes are totally rust and crud free so I leave 'em be.
 
Front ones on these can be a real PITA depending on how stuck they are. I may be mistaken but IIRC these are the ones I had to use a 7/8 6pt wrench on and drop the pipe because I couldn't get a socket on. Check first before buying parts.
 
There is a way to test the sensors. Me thinks if they test ok you will not see benefits to replacing them.
 
Originally Posted By: Chris142
I replaced the uppers on my jeep @110k. Made a huge improvement in power, mpg and response. It did not throw any codes.


Some engine types have just one upstream and one downstream.
I got an upstream for $25 off eBay and it was an ACDelco too.
 
When my Suburban hit about 120,000 miles, it threw an 02 sensor code. I changed all four of them and noticed an immediate improvement in the way the truck ran, slight mileage increase and more throttle response.
Separate note, recently, I had to replace mt drive by wire throttle body because it kept putting on the CEL with a TPS code. Again, the truck runs a little nicer.
I've always wondered if sensors got lazy with age, like they're not throwing a code but they're not as sharp as when they are new. It certainly seems that way to me.
 
I usually change upstream sensors at around 100k. Many times it will improve mpg. Downstream sensors only need to be changed if they fail.
 
Down stream O2 sensors don't normally affect driveability or fuel economy. The upstream sensor looks at the fuel mixture coming out of the engine and normally swings up and down. The catalytic converter should be able to absorb this mixture swing and the downstream sensor should see a relatively steady flow of exhaust gas and O2 mixture. If the cat is not working properly and can't even out the O2 mixture, then the downstream sensor sees this and sets a code for inoperative CAT. If you are not getting a code for this, there's no reason to change the downstream O2 sensors.
 
Ditto the above. Just change out the 2 upstream sensors, leave the downstream ones alone. Had one car where I changed them out at around 120k, gas mileage improved. The original downstream ones were still there in 200K plus. They get lazy as they age so you can replace them earlier before it throws a code. The Oxygen sensor people say to replace them every 60-80k so at 112k, you're probably due soon anyway.
 
Is a bad O2 sensor going to leave you stuck on the side of the road?
 
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