99 GLE, Pearl Blue, 90k

I've been getting horrible MPG the last year or so, but it has been getting noticably worse. I've been pretty good about oil changes, air filters etc.

I usually drive city mostly, and since my office is only a few miles away I usually only fill up my tank about once a month.

However my last tank I did do quite a bit of highway driving as well and got only 250 miles on a tank

I noticed a few posts about replacing the O2 sensor a usenet post about replacing a coolant temp sensor. Do you think replacing these might fix the problem?

If so, is this something I should just buy the parts online and bring to my mechanic?

Thanks!

-Mike

 

You can try your basic gas mileage tune up:

-Properly inflate your tires
-Change your spark plugs
-Change your filter

 

i would check to see if you have any codes first.
Could be your KS

 

KS = Knock Sensor?

 

Correct-even if it is that, don't expect amazing gas mileage if you're driving mostly city though.

 

prob running rich.

 

I just dropped the car off at my local mech, and he said there are 3 O2 sensors and 2 knock sensors. He said he will hook my car up to the computer and see what it returns.

I've read on posts here people saying to replace the sensors, are they talking about ALL of them? How much should the 3 O2 sensors and 2 KS cost?

 

I don't think your mech is very familiar with Maximas. s/b only 1 KS. You might want to learn a bit more about the car, so you don't get ripped off.

 

2 knock sensors? Please take your car to a different mechanic...

Oh, and if all of your o2 sensors were gone your car would barely run.

 

lol he tells you theres two so he charges you double

 

Also the rear O2 sensor near the cat doesn't really affect gas mileage.

 

1. See what codes are running, if you are throwing a KS code that can have a significant effect on your gas mileage. You always check for codes first when trying to figure out what any problem is.

2. Check the basic stuff, have you changed your oil lately? Fuel filter? Do your tires have the correct amount of pressure? Are you driving the car hard? Your driving habits have a big impact on gas mileage. Have you changed your spark plugs lately? Inspect the coil packs.

I'm pretty sure you are going to throw a KS code since almost every Maxima I've run across has had that code.

 

Someone could be stealing your gas. Are you using Ethanol?

 

Thanks for the tips guys. I will get the codes from the shop and report them here. To be fair, the guy at the shop I talked to doesn't work much on cars anymore. The good thing is this shop has a stellar reputation for being honest.

I'll bump this Monday when the codes come in.

Thanks again!

 

Why don't you check them yourself? You own a screwdriver don't ya?

 

Or if you doubt yourself, go to autozone or one of those free people and use their scanner.Also, they normally say once one 02 goes, the rest of them will start acting up(this did happen to me), nonetheless its really expensive to change all of them one time.