Just crawl under the truck and start at the rear where the evap box is. Check all the lines from the box all the way to the engine. Also check your filler neck for any damage. I had this happen with my bl i just had to resecure the fillerneck extension.
That's a great Idea CRDLIBERTY! You get the ball rolling and I'll gladly add my vote. I have no idea if age is a factor or not but obviously there are a lot of people here reading bad knock sensors and considering it's mostly a silent problem you know a lot more people have issues with them that simply don't know.
Believe it or not When i was investigating this months back I called up a few Nissan service managers and more than one said that many of the frontiers had issues with this, one guy admitted to probably more than half have bad knock sensors. So it's obviously a manufacturing defect or bad sensor placement. I was also told by them that I could probably just let it go or try switching to a higher grade fuel.
If however you do need to get this thing fixed, it's quite involved labor wise and I was quoted something like 6-8 hours. Nissan would take a huge $$ hit to recall this, so sadly I don't see anything coming out of it, but don't let that stop you from trying
It was told to me that it retards timing in situations where it detects knocks, and that knocks usually occur when hitting the peddle hard, climbing a steep grade or towing something heavy, basically putting a lot of strain on the engine. However I've towed heavy loads and never had a problem. So even in situations where it might be a factor I've not had any issues with knocking and I use 87 octane as well, so go figure. So long as it doesn't pose a real threat I'll never fix it.
Yes a lot of the knock sensors on Frontiers/Xterras are bad. You won't even realize it because it won't light up the MIL.
Anyways I looked at the EVAP lines and I can't find anything. There are tests I can do but it requires a special pump and leak detectors and I don't have those. I've heard you can smoke test it but I don't have that equipment either. It doesn't effect the engine and I don't have to worry about emissions so I guess I'm stuck with the MIL on.
I know i'm kinda late on the info here.. But this is a very common thing.
I think its more common with the S/C models, mainly because the requirement for premium fuel.
I have a S/C model, and anytime i have regular unleaded put in the truck (by accident, full service idiot, or wife) I get the knock sensor, and sometimes EVAP also... I run some Chevron Techtron through it, and a few miles later, its gone... The one time i got the EVAP, i stopped into AutoZone... they wouldn't clear it, but read it and let me use there set up to clear my code... and its gone...
Usually the cause of this will be due to recent fill up, and gas octain wasn't up to par.. Or... if you run really low on gas and cause it to suck up some junk...
Nothing to worry about though... defanately normal to say the least...
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