Bad gas mileage...O2 Sensor?

[soundmanlpte]

My MPG are down to under 16 mpg. This seems low to me. I've been considering replacing the O2 sensors as I am sure this has never been done. Could that cause the low mileage? Could a bad fuel pump cause this?

 

[weekendclimber]

I'm no expert, but from what I've gathered from this site and others is the O2 sensor could definitely be the cause. There are several threads on replacing it on here and it's a pretty simple job. Just need a wrench (12mm or 14mm I think) and maybe some PB Blaster if the nuts are rusted. I think new sensors can be had for $50 or so. Make sure to get Denso.

 

[JayRolla]

My MPG are down to under 16 mpg. This seems low to me. I've been considering replacing the O2 sensors as I am sure this has never been done. Could that cause the low mileage? Could a bad fuel pump cause this?

If you not throwing a CEL than most likely the o2 is fine. But it could cause low mileage.

But again 16mpg is not bad gas mileage on this vehicle. Per Toyota a NEW 4runner v6 auto, 4x4 gets 15mpg city. 16mpg combined and 18mpg Highway. I dont see where your mileage is bad? I see you have 196k miles on your vehicle. I think your doing fine.

 

[soundmanlpte]

Cool thanks for the help guys. You may be right Jay. It may just be city mileage. However, I have averaged 19 and gone up to 22 with this truck. Also, Hayness manual lists O2 sensors as regular maintenence at 80k. And since it's so simple I will probably swap them out when I get some extra money. Can't hurt.

 

[nissanh]

It really hurts to see such a big drop. I used to get 21.5 MPG on highways and now it is 17-18 MPG for no reason. replaced many parts and no improvement.

these days you get a gallon for like $2.40 right? Yey!

 

[soundmanlpte]

True that! Guess I shouldn't complain much. I'm filling up for under $35 right now!