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why do we need a knock sensor?

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Old 03-29-2003, 06:10 PM
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why do we need a knock sensor?

i know the knock sensor is used to help protect the engine (pistons?) from poor combustion with lower grade gas, but if we run premium do we really need a knock sensor

my CEL gives a knock sensor error....when it does this i guess it usually needs to be replaced?

i see the sensor in my car, but i cant figure out how the heck to get in there and change it (im not too handy)

anyways i guess im gonna have nissan do it when they check my airbags, does anyone know how much this would cost?

thanks
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Old 03-29-2003, 07:02 PM
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Re: why do we need a knock sensor?

Originally posted by wrongway15
i know the knock sensor is used to help protect the engine (pistons?) from poor combustion with lower grade gas, but if we run premium do we really need a knock sensor


And from other, more dangerous things, like running too lean.

my CEL gives a knock sensor error....when it does this i guess it usually needs to be replaced?


Not true - Sometimes it does, sometimes it doesn't. If it comes on with another code, most likely it's trying to tell you something, and is working fine. Buy a Chilton's manual and use a multimeter to test it.

i see the sensor in my car, but i cant figure out how the heck to get in there and change it (im not too handy)


Buy a Chilton's manual at your local auto parts store.
anyways i guess im gonna have nissan do it when they check my airbags, does anyone know how much this would cost?


They'll rape you. It's a stealership, after all.

thanks
You're welcome.
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Old 03-29-2003, 08:33 PM
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thank god for the quote feature
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Old 03-30-2003, 11:21 AM
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guess id never thought about running too rich
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Old 03-30-2003, 11:44 AM
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Originally posted by wrongway15
guess id never thought about running too rich
Rich doesn't make you misfire or knock - lean does.

Rich just gives you bad gas mileage/loss of power.
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Old 03-30-2003, 05:06 PM
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i got a CEL for knock sensor as well.....no other codes....
is this something i should worry about? how much do these go for?
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Old 03-30-2003, 05:51 PM
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so people waste money when thier 02 sensor goes.. its a gimic from the nissan dealer
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Old 03-30-2003, 11:05 PM
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why is a o2 sensor bs?
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Old 03-31-2003, 06:33 AM
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Originally posted by wrongway15
why is a o2 sensor bs?
Because a bad O2 sensor can trigger a code for knock sensor even if there is really nothing wrong with the knock sensor.
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Old 03-31-2003, 08:34 AM
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The question I have is could the 02 sensor be responsible if
you're 'ONLY' getting a knock sensor code?
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Old 03-31-2003, 09:52 PM
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well i have an knock sensor code and an undefined code...o2 sensor maybe?

can i take this to a regular mechanic and not nissan?

Originally posted by Slowpoke

Because a bad O2 sensor can trigger a code for knock sensor even if there is really nothing wrong with the knock sensor.
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Old 04-01-2003, 01:02 PM
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wow, this should really be addressed in a sticky or FAQ. anyways, heres some more info.

- you get a knock sensor code with an O2 code because the ks code is a piggy back code. if you have a bad O2 sensor, it'll create a ks code. if you have a evap problem, it'll trigger a ks code.

- if you actually do have a ks problem, buy a chiltons or haynes manual and read up on how to physically check your ks before you buy a new one.

- a few members have decided not to replace their ks and use a series of resistors to make the car think there is a ks there by replicating the same voltage and ohms the ks would put out. i did this to my friend's O2 sensor on his contour svt and he noticed it ran better and had better low end torque. the disadavantage to this is that, like Ian said, this can damage your engine.
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Old 05-01-2003, 01:09 PM
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Might be a little late but...

If you still want/need to change your KS, here's a "do it yourself" link:

http://www.skippynet.com/maxima/knocksensor.htm

I've heard of dealerships quoting $400 to $600 to do this saying they have to pull the intake manifiold to get to the KS. You can do it (without pulling the manifold) in about 10 minutes for the price of a couple of tools (if you don't already have them) and a KS for about $120 - $130.
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Old 05-01-2003, 03:25 PM
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daym.. does anyone have a write up of how to check the ks with a multimeter, cuz i get the ks code and my car has real sh!tty gas mileage, like 220 a tank.. i just ordered a new ks and should be comin in next week but i dont wanna replace it if nothing is wrong with it.. also if it does end up being something else, how do i know which o2 sensor or if its an evap problem if my ecu is only throwin the ks code.?? i got a 97 SE w/ 65,000 miles on it..
thanx..
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