Worth it to change upstream Air-Fuel sensors? (no code thrown)

[zman1968]

Howdy Inmates,

Over the years, I've beefed up my '03 4Runner with all the offroad capabilities and it has added a lot of weight, and predictably, lowered gas mileage.

Been reading tons of threads about codes thrown or *how* to change the sensors, but haven't found any "is it worth it" threads, so hoping this isn't a redundant post.

No issues with my almost 20-year-old sensors and no codes thrown to date.

Would it be worth it to spend $279 to replace the 2 upstream air/fuel sensors? Would my gas mileage improvement even be noticeable enough to justify the cost or should I just wait for a future issue before dropping the bucks?

Note I live in a hilly area and I get about 13 mpg around town, maybe 19 or 20 hwy if I keep it at 65ish.

 

[AuSeeker]

Howdy Inmates,

Over the years, I've beefed up my '03 4Runner with all the offroad capabilities and it has added a lot of weight, and predictably, lowered gas mileage.

Been reading tons of threads about codes thrown or *how* to change the sensors, but haven't found any "is it worth it" threads, so hoping this isn't a redundant post.

No issues with my almost 20-year-old sensors and no codes thrown to date.

Would it be worth it to spend $279 to replace the 2 upstream air/fuel sensors? Would my gas mileage improvement even be noticeable enough to justify the cost or should I just wait for a future issue before dropping the bucks?

Note I live in a hilly area and I get about 13 mpg around town, maybe 19 or 20 hwy if I keep it at 65ish.

If the old AF sensors aren't throwing codes then they are doing their job within the specs Toyota set for your engine, new ones aren't going to do any better job than the ones you have that are still do the job they were designed for.

It would be a waste of money, it won't increase your gas mileage.

That all be said, spark plugs if they haven't been changed in a while "might" improve the mileage a little, cleaning your throttle body if it hasn't been done in a while "might" improve the mileage a little, making sure your calipers are not or about to seize and if they are replacing them "should" improve your mileage a little bit.....but from what you say about your T4R, I would assume it has bigger than stock tires, a lift, probably after market heavy bumpers, maybe even a winch, if so then your mileage is about up to par with most everyone else's that has those MODS, or maybe it's just those HILLS, but your highway mileage is very good, especially if you have the aforementioned MODS.

 

[zman1968]

Thanks AuSeeker. As it happens, I have been doing some other "treatments" in that arena. I replaced the spark plugs about 15k miles ago and the MAF 8k miles ago. I am planning on cleaning the throttle body again (been about 3 years) and replacing the o-ring for it as well.

Also, yes, I have all of those mods you mentioned in my signature. And the good highway mileage is on flat ground. Once the hills are in play, it drops for sure. Appreciate your feedback, brother.

 

[4RunnerAquasport]

Finding a tail wind is the only thing that helps my mileage, especially the 5th gen, which weighs 6k lbs+ w all the extras.

Hills? I lose a 1/4 mile per gallon every time I come up on an interstate overpass.

One word of advice for those buying plugs, sensors and ignition parts. Be wary of boot legs. The part numbers, packaging, and appearance of these products are quite convincing. Pay the extra scratch for OEM vendors and part numbers.

Toyotas have always responded better to these parts.