Now im new to vehicles kind of. but so far i never delt with a o2 sensor. i purchased a truck and the check engine light was on so i brought it to school and hooked up the scanner and scaned for codes but nathing came up. so i started going on the random pages on the scanner to see if i could find any thing odd. then i came across the o2 sensor. it was giving off to high of numbers then to low of numbers so. that must be it. So does it pay to get an o2 sensor. cause i heard if your o2 sensor is bad it will give you bad gas milage. and when your saving money to get new toys. it just might help. so does it pay to get a new one?????

 

An oxygen sensor will run probably somewhere in the $50-$60 range.

It's my understanding that if the computer has flagged it as a bad input, then a default operating strategy will be used. The O2 sensor should be the final tweak in the adjustments, other measured parameters such as air flow should carry the bulk of the load.

Your mileage will likely suffer somewhat with a failed O2 sensor, but it takes a lot of miles to make up the cost of the new sensor.

All that being said, I would first recommend to verify that the sensor is bad - if the 'check engine' light was on, there should be a definite code stored. In other words, be sure you're fixing the right problem. Was the O2 sensor reading too high and too low because it is faulty, or is there something else going on to cause these readings?

Whatever the problem, I recommend to correct it. It's been my experience that too many times, problems bring on more problems.

 

their was no codes or any thing like that. my teacher even did it to see if i was doing it right and no codes came up. now i am getting 12 mpg on the truck. i do have another truck just like that except it have 2wd and a stick. and i was getting 17 - 19 mpg on that. to me that seem like a big jump from going to a auto with 4wd. right?

 

To share my experiences - I'm getting about 10 around town, 13 on the highway with my setup and this has been fairly constant throughout its life. Only thing different from stock are the wheels & tires, and I do correct the mileage for the difference in tire size - amounts to about a +10% correction from actual measured mileage. Fortunately, I don't rack up the miles like I used to, so it's not a bank-buster.

I'm thinking it should do better, but for the life of me, after 15 years haven't been able to figure it out. I do keep it in good tune, and am all over any 'check engine' codes that pop up.

Due to the additional weight of a 4WD with its transfer case and front end, and that it typically sits higher which presents more underbody wind drag - it's normal for a 4WD to have less fuel economy than its 2WD sibling. How much less is considered reasonable, I don't know.

 

wow 13 on the high way you must have large tires on it?

 

My 96 F150 4x4 5.8 was getting 13mpg around town and 17-18 on the highway during the summer/fall/early winter. Now, with the crappy winter gas, I am getting 10-11 around town. I have not done any serious highway driving recently so I am not sure what my highway mpg is down to.

 

Nah, just big enough to make the truck 'sit' right with respect to the ride height, instead of daintily tippy-toeing on down the road as it looked with the stock tires - see sig - 31x10.50R15s, which are about 10% taller than the stock tires.

Dewman brings up a point - winter-blends of gas are slightly lower in octane as compared to summer-blends, although it's my understanding they still have to meet the minimums posted on the pumps. The lower octane and other chemical wizardry helps with cold-weather starts and operation, but unfortunately at a cost of a little bit of fuel economy.

 

now i have the 4.9 i should get15 to 17 anytime even with the auto trans right