Car info:
106K and everything stock.

I read through the KS threads and I'm still not 100% clear on something.

Can a KS go bad without pulling any codes nor setting off the ECL? I used an OBD-II reader. Has anyone replaced their KS without pulling any codes but suspecting their KS was bad?

I was getting around 420 miles (average) on a full tank and all of a sudden, i would only get 375 miles (MAX). And my driving didn't change and i fill roughly the same amount so the miles/gal is pretty accurate. I do all the basic maintenance on schedule (tire pressure at max psi of tire rating, plugs, fuild changes). I've changed front and rear O2 sensors (1 went bad). I changed my TPS because the resistance check wasn't coming out (no ECL) and someone said this could have been 1 of the gas mileage problem. This mileage change have been going on for a while and my car runs fine. The only thing I can think of relating to fixing the gas mileage is the KS and maybe giving the intake manifold a real good cleaning on the inside (including IACV). However, I don't want to dump that much cash on the KS only to find out nothing was wrong with it.

Didn't mean to write so much on the mileage part but I had to explain why I'm asking about the KS.

Thanks in advance.

 

If you mean can the KS be bad w/o a CEL, then yes.


Why would you if it(CEL) only takes 1 mintue to check?

 

NmexMAX,

Thanks for responding. The questions is, can it be bad without a CEL AND no codes?? I've seen posts that say it doesn't trigger a CEL but it will have codes if you check.

Why would someone replace it? In hopes that it will solve the bad gas mileage problem. I've seen so many post on poor mileage, I thought someone might have replaced the KS to help solve the problem.

 

You can always test it to see if it is really bad: Knock Sensor Diagnosis, Test and Installation

 

honestly, 375 is not bad if you ask me. I would love to get that, I get 180-200, w/ all maintenance done, including the KS & o2 sensors. now, that is bad. anyway, if you'd like to check it manually just for peace of mind, you can use a multimeter. follow polarisdb's link.

 

magic_max,

Is it possible that your change in MPG coincided with gas additives in your area changing from MBTE to ethanol? From what I've read, that could account for some MPG loss.

 

I thought that the knock sensor did not affect gas mileage?

 

I thought Elvis was still alive..

 

Haha...elvis comment.

It's not the change in gas additives because the drop happened a couple years ago. After reading what other people's mileages were, I'm pretty happy with mine but considering i was getting quite a bit more and to all of a sudden drop is what bothers me. I'll just take it off and do a multimeter check.

Thanks for the replies.