Out of curiousity the other day I decided to try and pull codes from my car as I had never tried it before. I ended up getting 0304. The most recent time I checked my mileage I got 21.2mpg and that is mostly stop/go city driving not highway so I wouldn't think my mileage is that low. How much should I expect to gain by doing the knock sensor?

 

KS is only $64 shipped on ebay, so might as well replace it. It definitely won't hurt you mileage and will help some, and you might regain some lost power as well. So go ahead and replace it. I ordered mine today.

 

for real, i always wondered, but i think it varies though, some guys get a way high percentage increase that others....thats just what i think so i stand to be corrected....

 

you won't get much improvement in mileage. it's only under heavy acceleration, or cruising at hwy speeds that it has an impact on timing. so if you're not a leadfoot, and don't cruise on the highway much, then you won't notice a big difference. I'd expect maybe 1-2 mpg at most.

FYI - according to the FSM, the knock sensor is not really an active knock management system. it is only there as a fail safe against knock induced by cheap gas. of course, if you have the KS code your ECU reverts to a "safe" timing map that doesn't care what the octane of your gas is. it's only after you fix the KS and reset the code that the ECU goes back to the "optimum" timing map that requires 91 octane or higher gas. so even though the KS is just a fail safe, you will still see some improved performance by replacing it.

 

yeah i plan on replacing it regardless, i was just curious about what to expect. i just got done reading the motorvate write up so I think after christmas (damn gifts cutting into my personal expenditure funds) I will be ordering one and doing it.

 

I got 21mpg city on a good knock sensor. That's also the average for city driving according to Nissan.

 

Agree with all above. If you track your milage and you note heavy decrease like I did....was getting around 15/16 city and had the KS cel...once you replace you'll experience definite increase in acceleration from stop as well as posted numbers by nissan at 18/city and 27/hwy.

If you're pulling the code...replace it..definitely worth doing yourself...dealer will charge you upwards of $450-$500....total rip off....with the right tools and patience should take you at most 25 minutes...hardest part for me was getting the darn replacement back where it comes from...get your girlfriend (assuming she has small hands and doesn't mind getting dirty) to position the knock sensor in place and hand tighten it....then torque it down with the appropriate socket.

You probably already know this but if not....there's a great sticky on this in the FAQ's.

Good Luck.

 

all i know is that my knock sensor went out 2 weeks ago.
i used to get 330 miles a tank on avg. now, ever since i got the knock sensor code, i've been getting no more than 280.
I suggest replace it or you will get the mileage of a v8 but performance of a v6. just got mine today, cant wait to replace it.

 

I took a sginificant hit when my KS went bad, and performance to boot. I think my highway milage dropped from 26-27 to under 20MPG.

 

I used to get about 26 hwy and about 24 city. Then I started getting about 22 with a mix. So I just replaced KS and have not noticed any increase. I do not have a heavy foot, but will go WOT once or twice a tank.
On the other hand, I now have an o2 code, so that might be the culprit there...hopefully.

 

Hmm well like I said I had never pulled codes before so I have no idea how long the KS has been bad. Maybe as long as I've had the car as I never noticed a performance decrease. Anyway like I said I will be changing it after christmas when I have some spare change for it.

 

I ordered mine the other day, hope to recieve and replace asap. Fuel economy has been 22 with mostly hiway driving, and no torque under normal driving conditions where the RPM rarely exceeds 3K. Yuck