# Knock sensor



## Zilla (Oct 9, 2007)

Just ran my codes and I guess my knock sensor is dead as well as both the front left "02 sensor heater" and the front right 02 sensor "heater". 

What is an 02 sensor heater, and how do I replace it?

Anyways, I read that in order to replace the knock sensor, you must drain the coolant? Does this sound right?

Thanks.


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## Vangtastic97 (Dec 21, 2007)

the knock sensor can be replaced without draining anything and without removing the upper intake manifold. It's just going to be rough fitting your hand under the manifold. If you have a stock y-pipe, replacing the O2 sensors will be tough as well. You can buy the sensors at autozone.


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## Jeff (Oct 17, 2002)

Whoa...
...The 2 o2 sensor codes could definitely be tripping your knock sensor code. Replace those first and then, if a ks code is still present, replace your knock sensor.

You can buy from Autozone but it may be cheaper to order them online as well. Look to spend around $60, iirc. 
Oxygensensors.com - $50-70 <-click
Pinnacle Nissan OEM sensor - $108.47 <-click


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## Culver (Feb 17, 2008)

the ecu will not throw a Knock Sensor code alone, it will always come with an another code probably an 02. the cat 02 is a 4 wire, which is heated, the other 2 are 3 wire. i use universal o2's from ebay which cost about $20. good idea to replace the k/s too as it will really pick up your low end torque. you can read and reset your ecu by yourself. i got an k/s delivered for $50 where the dealer wanted $250 and $140 for the o2's.


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## Jeff (Oct 17, 2002)

The KS can have its own code...but most of the time it results from another problem. Just wanted to add that it can throw its own code rarely.

You also DO NOT need to change the KS if you have an accompanying code (i.e. coil pack misfire, o2 sensor)
It's a waste of money. Change out whatever is causing the accompanying code FIRST and if the knock sensor still gives problems then go ahead with changing it.


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## Culver (Feb 17, 2008)

Jeff said:


> The KS can have its own code...but most of the time it results from another problem. Just wanted to add that it can throw its own code rarely.
> 
> You also DO NOT need to change the KS if you have an accompanying code (i.e. coil pack misfire, o2 sensor)
> It's a waste of money. Change out whatever is causing the accompanying code FIRST and if the knock sensor still gives problems then go ahead with changing it.


I agree, although I never heard of a k/s throwing its own code. I think the k/s is a good thing to change if its old as the general consensus is that a new one will improve low end torque, noticeably. Someone should make an extended magnetic ratchet that will fit under the manifold.


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