I just looked up the O2 sensor and it's about $120 from NAPA for my '95 4Runner 3.0.

So what exactly does that get me?

Is it really a required or even worthwhile replacement?

I'm getting 17mpg now, will that increase significantly?

 

Check your owner's manual. Toyota does replace some of them for free at 80K miles.
I'm sure someone here can detail the procedure for checking to see if your's is bad or not. It's real simple on the '89s.
$120 sounds about right for the NAPA part, but I've heard of many people switching back to the OEM sensor for a variety of reasons.
17mpg is about right for a 2-ton vehicle with the 3.0. You might see some improvement with a new sensor, but don't expect to be breaking into the 20's.

 

I just swapped out mine. Already have seen a slight improvement in milage but a noticable loss of power as the engine was running rich before. Im going to wait 2-3 tanks before I come to any conclusions though. A mechanic told me that the ECU would fully reset to the new O2 sensor after about 60 keystarts.....thoughts?

My freak-of-nature-3.0 just broke into 20-21mpg on this last trip home. Got 165 miles on 1/2 tank doing 70mph, I'll know exact numbers when I fill up again. (no racks, no big tires, 4.11 gear, 50psi, no gunning, no hills, the FL norm...)


Hope for 20, but as the previous poster stated, don't expect it. Most 3.0s seem to be lucky to get 17....

 

Forgive my ignorance, but if the fuel economy might only be mildly affected (Not enough to warrant $120 and time to install)....what is the point in changing it at all? I know it's a periodic maitenance item....I just don't understand why (unlike fluids and lubricants that wear down and can decrease component life if not changed regularly).

Thanks,
Russ

 

O2 sensor, shipped to your front door for $89.26. Some parts you might be able to get away with subbing out at after market stores but I wouldn't do it with 02 sensors. Actually I don't recommend it at all but thats just from what I see everyday from those that do. If you are interested let me know.


Todd

 

Sounds like a pretty good price.

Can you answer my question about "why" someone should change it in the first place?

 

O2 sensors don't really 'wear out', but they do corrode - the exhaust stream is a nasty place to be. Some of the material in the sensor may even be sacrificial(sp?).
Still hoping someone can post the test procedures for your '95.

 

I don't mind replacing something if it's needed and beneficial, just don't want to do it for no good reason

Thanks again,
Russ

 

Here is my thought train on the matter. It's probably incorrect, and if so, someone correct me.


When the O2 sensor goes dead, the ECU for whatever reason seems to make the engine run very rich. (Lack of O2 in the exhuast indicating lean conditions?) Doing this for a long period of time makes the injectors fire off the most fuel they can, meaning really loud injector noise. I don't know if the injectors would fail after a while, but them going wide arse open can't help their life expectancy and it certainly wouldn't help in keeping them clean....

Then I heard something about a rich exhuast killing/clogging catalytic converters....

Besides, if you plan on keeping your yota for a long period of time, it should pay for itself.

Steve

 

I replaced mine because it made my check engine light come on at about 81K mi. At that point it began to run real rough and hesitated quite a bit. I think (guessing here) when the O2 sensor is out of spec, the ECU just disregards the signal and relies on the MAF, TPS and the preprogrammed fuel curve in the Eprom chip. The lack of an O2 signal just doesn't give the ECU a feedback to correct for.

It is also the main reason why I have my OBD II code reader from www.Auterraweb.com .....I love it!

After replacing it my truck runs ike a million bucks again, but mine was bad enuf to set off the engine light tho.

 

Can you just clean the o2 sensor and see any improvements??

 

I don't think so since it has a special coating on it but I could be wrong......if it were me I wouldn't chance it and just pay up for anew one.

 

Yeah cleaning it will do no good just get ya a new one.

Todd

 

yeah so how do you know if its bad? other than having the check engine light on? i just bought my 4Runner about 4 months ago and don't have any maintanace records.

 

that is a good price, where could i get one for that? and is that one just a plug in, no splicing required?

 

Dude, that is a smokin' price....I forget what I got ripped off for at the stealership but way more than that.

 

It is not fun.....don't burn yourself.

You need to probe it hot (ie car warmed up) with a DMM and see if it is still within the specs.

or......you can do what I did and get the OBD palm device from www.Auterraweb.com and look at the sensor voltages while driving. There are other OBD devices out there that I think will do similar but I don't have any of them so I can't speak to it.

 

what is a DMM and where do i get it? im just trying to help out my gas milage a little.

 

Sorry Digital Multi Meter......any hardware place or good auto store should have one. Even the cheap ones do quite a bit (got one for $10 at Walmart). You just need the basic stuff, volts, amps, ohms, diode test, continuity......capacitance is nice to have but usually much more $$$

 

and what i just look in the owners manual and look at how many volts are going throught it or something?