Lately i see a lot of posts about failing knock sensors. Does that have anything to do with people replacing their stock intakes? I dont see any correlation, but it seems most of those cars have aftermarket intakes.
Can someone clear this up for me?

 

if you've ever seen one you'd be surprised they last more then a year for what they put up with, they just happen to last 5 years or so and a lot of guys are getting to be that old.

 

But if the knock sensor has to work overtime, wouldn't that mean that the engine is suffering big time? as far as i know, you get the knocking from poor fuel, low octane gas, timing that needs to be adjusted, and so forth. knocking=detonation? detonation=real bad.
am i making sense?

 

when the knock sensor goes bad it goes into what is called "fail safe" mode which it makes the car think of the worst possible situation and retards the timing to that, it's for safety. it's like the transmission resistor mod on a 4th gen, if you take the resistor out of the loop it ups your line pressure, higher pressure is better then lower. your engine will never knock.

 

but is there any correlation to the mods? or is it "just happens no matter what"? i'm thinking of doing my intake, but if i have to start changing knock sensor several times a year (or even once a year), he'll beat me silly with a torque wrench and top it off with an impact gun!
seriously though, i need to figure out why its happening.

 

I think your assuming that the failures are related to a sensor that is being overworked because of the mods everyone is using. I think the sensor is subject to a pretty harsh environment and is a life limited part. I hadn't heard the five year number before, but it makes sense since a lot of the fourth gens that have had the failure are around that time frame. I also noticed that they seem to be in the colder climates as well. Maybe the stress of going from cold temps to the normal operating temps repeatedly takes a greater toll on it too.

 

I got 96 in NYC, and i dont know if mine was ever changed, cause i got it on christmas 2001

 

The KS sits on the top of the engine, where it is subject to 300+ degree temps, moistur and vibration. While it is a rather simple piece of plastic, the inside is a delicate piezoelectric element that can only take so much abuse. A five year 'life' may be quite reasonable.

 

so is there any simple way to tell that you have a failed knock sensor if it is auomatically hold back the engine other then lower performance?

Is there anything I can do to check or do I have to take it to the mechanic?

 

simply check your ecu and see of you pull a 0304 code.

 

yeah, I don't have anything to read the ecu codes. I can check and fix mechanical things, but i don't really mess with the electircal stuff.

I was hoping it was like a fuse or someting you can physically inspect - I guess I'll wait until I go to the shop next time. If the car is running with a failed knock sensor it can continue to do so for a while longer.

 

to get back to my original question - goes installing an aftermarket intake/doing OSCAI have any direct relationship to knock sensor failure? or does it fail because of the harsh underhood conditions?

 

All you need is a little screwdriver and the ability to count flashes on the CEL and you can pull the codes yourself.

 

I don't think it has anything to do with intakes. My sister just had her's replaced and her car is stock other then springs. Btw... that's in Washington State and a 95 GXE. I'm going to go check mine right now.

 

nothing to do with it, the one on my 95 was bad when i got the car, STOCK. and i never fixed it.

 

im having my kock sensor done in a week. Shouldnt cost me more than $140 installed for a genuine Nissan part.

Ant

 

has any body tried to fix or clean the thing them selfs? Like a last dich effort before haveing it replased. Or is it to hard to get to?

 

hard to get to and not fixable, if you get it out you replace it.

 

I new my car seemed slower dose any one know how much power is being lost?

 

10% prolly

 

I just changed mine and after beating up my hands and seeing what a PITA it is to get out, the LAST thing in the world I would want to do is try to fix it and then have to replace it anyway. The odds of it being something fixable are pretty low. I don't think you have a prayer of actually fixing the knock sensor itself, but if the problem were an electrical connection somewhere it might be doable.

 

Along with crappy gas mileage.

SuDZ

 

ugh..my CEL came on today with the knock sensor failure..
how much does it cost just for the part(no labor)? i called autozone but they said its a dealer only part and they arent open until monday.


thanks

 

I thought the KS didnt trip the CEL?

 

it does

 

Mine doesn't and according to my FSM the KS DOESN'T trip the CEL. I have a KS code in my computer and it didn't trip the CEL. You don't have a 2nd code in there do you?

 

How did you replace it? Did you take the intake off or did you just wedge your hand and a wrench into the intake gap? If you did it this way, did you disconnect anything to get more room? I see some sensor connections around the area.

 

I heard it is tripped normally in conjunction with something else failing, like the O2 sensor (front one). Normally the KS doesn't trip it, but it could.

 

the KS ALONE will not trip the CEL.

 

I just squeezed my hand into the gap under the intake. I didn't need to disconnect anything, the only parts that were in the way were solid metal and not moving. Once you get your hand past the turn and under the intake, there is plenty of room to move around down there.

 

I have personally seen the the CEL come on with only 0304 registering when I read the codes.

 

It all sounds so dirty somehow.

 

thats what happened to me last night

 

Add me to the list. I just pulled the code myself.

 

Welcome to the club.

 

I actually edited that so it sounded better too.

 

What kind of transducer is the KS? Does it vary it's resistance or change the voltage signal to the ECU? Just wondering if we could replace it with a fixed resistor or component so that it would read a constant "no knock." I've never used anything less than Premium in my car and have got to believe that the occurance of knocking would be very rare.

 

hmm weird i did some errands today and the CEL never came on

 

So it can be assesed that as long as the light isn't on, don't worry about it, right?

 

wrong, it's a silent defect,. you have to run the diagnostic mode to get it to spit out the code. if you get the code, replace it.