Poor gas mileage? I used to get close to 30 MPG now maybe 18-20 the highway?

MIKE**

MEMBER
2012 NISSAN ALTIMA
2.5L
4 CYL
2WD
AUTOMATIC
148,000 MILES

I used to get close to 30 MPG now maybe 18-20 the highway, in town maybe 15 or less. I have a MPG indicator that fluctuates quite a bit on an even level road at a constant speed, but give it a touch of gas to keep up the speed it goes to almost zero.

3 Replies

KEN L

MASTER CERTIFIED MECHANIC
47,643 POSTS

The number one reason for the low miles on this car is a bad MAF sensor which is easy to change. Also, I would check the air pressure in your tires.

Here is a guide to help you and I have the location of MAF sensor in the diagrams below:

https://www.2carpros.com/articles/how-to-use-a-tire-pressure-gauge

Check out the diagrams (below). Please let us know what happens.

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Friday, August 5th, 2022 AT 5:29 PM

MIKE**

MEMBER
3 POSTS

I believe what you're saying, however I put this on a diagnostic computer and it came up with the air/fuel sensor right behind the radiator. Keeping in mind that the car runs great, idles fine and plenty of power, no hesitation whatsoever. I just don't want to start replacing parts unnecessarily. It just got horrible gas milage and it just started out of the blue. Air pressure is good, always around 32 -35 lbs. On Michelin tires.

Thank you very much for your answer. But you could reply to the air /fuel sensor issue if you think that could be it also?

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Saturday, August 6th, 2022 AT 10:04 AM

KEN L

MASTER CERTIFIED MECHANIC
47,643 POSTS

No problem, sure it could be the air/fuel sensor #3 but I have seen the MAF cause more issues like this, but you can try it.

Have you run the codes?

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Check out the diagrams (below). Please let us know what happens.

Image (Click to make bigger)