Finally Checked My Ecu About My Cel
Finally Checked My Ecu About My Cel
I finally got around to checking my ECU to extract the codes. When I did, i got 0403, which is the knock sensor. I read in the Haynes manual that i have to remove both the upper and lower intake manifolds. Is this a difficult process? HOW MUCH WILL/SHOULD A KNOCK SENSOR RUN ME? HOW BAD, IS A BAD KNOCK SENSOR FOR THE ENGINE? 
(i'm still learning, please bare with me 
) Please respond. thanks!
(i'm still learning, please bare with me ) Please respond. thanks!
Member
Joined: Apr 2003
Posts: 67
I'll help you out before they lock this thread. Short answer is you don't have to remove the manifold.
Low cost knock sensor sources: The dealer will charge you $160 or so for the sensor. I purcahsed a Nissan OEM sensor off of EBAY for $90 shipped. I have seen them for as little as $80 and routinely for $100-$110. Search for both “Maxima knock” and “Nissan knock” to make sure you get all the possible matches. You can get a Bosch sensors for $115 shipped from http://www.nissanpartstore.com/nissan_knock_sensor.html I prefer OEM parts when possible and have no information on the Bosch.
Two good article on KS replacement:
http://www.skippynet.com/maxima/knocksensor.htm
http://www.motorvate.ca/mvp.php/507
Modifications to the Skippynet method
The article suggest using a 14” (or longer) ¼” socket extension to reach the KS retaining bolt. I found that using a 9” extension made it much easier to get the u-joint onto the KS bolt. To save money, I used two 3/8” drive extensions with a 3/8 to ¼ adapter, a ¼” drive u-joint and a ¼” 12mm socket (most of which I already had). Skippynet suggest using a 12mm flex socket, but being cheap I used a separate socket and u-joint so that I would have a more useful general purpose tool left over than the 12mm flex socket (better yet, I borrowed the u-joint and saved another $8). A 3/8” u-joint is a slightly bigger animal and in my opinion would make it hard to get the socket onto the bolt. It was not at all difficult to loosen the bolt using this setup. I had also borrowed a 16” extension and found it very difficult to get the socket onto the bolt head (I gave up after about 2 minutes, so it probably could have been done).
Once the bolt was out, I used a magnetic pickup to retrieve it (and eliminate the possibility of dropping it into the engine cavity where as you will find out soon, is not a very friendly place). With the bolt removed, you can pull the knock sensor out of the cavity by the harness and replace it. Next, I put the bolt into the new KS and used a small piece of tape to hold it in place while I stuffed it back into the engine cavity (again to eliminate the chance of dropping it in there).
Now the difficult part: I don’t see how you can locate the bolt into the hole and tighten it without stuffing your hand under the manifold. Others have reported that they used a claw type pickup to reposition the bolt in the KS, get the bolt started in the hole and then use the socket extension to tighten the bolt down.
If you have very large hands, you might try enlisting a girlfriend, your mom or a small child as others have done. I was able to get my hand in there and get the bolt hand tight, then it was just a matter of using the 9” extension/u-joint setup again to do the final tightening. Your hands will get cut up a little doing this, but no worse than I am used to with other auto repairs.
I was able to replace the KS in both cars in less than 1 hour including test drives using this method. The real key is using the skippynet socket extension method to crack the bolt loose. Once you have jammed your hand into the engine cavity you will realize how difficult it would have been to get a wrench on the bolt and loosen it.
Low cost knock sensor sources: The dealer will charge you $160 or so for the sensor. I purcahsed a Nissan OEM sensor off of EBAY for $90 shipped. I have seen them for as little as $80 and routinely for $100-$110. Search for both “Maxima knock” and “Nissan knock” to make sure you get all the possible matches. You can get a Bosch sensors for $115 shipped from http://www.nissanpartstore.com/nissan_knock_sensor.html I prefer OEM parts when possible and have no information on the Bosch.
Two good article on KS replacement:
http://www.skippynet.com/maxima/knocksensor.htm
http://www.motorvate.ca/mvp.php/507
Modifications to the Skippynet method
The article suggest using a 14” (or longer) ¼” socket extension to reach the KS retaining bolt. I found that using a 9” extension made it much easier to get the u-joint onto the KS bolt. To save money, I used two 3/8” drive extensions with a 3/8 to ¼ adapter, a ¼” drive u-joint and a ¼” 12mm socket (most of which I already had). Skippynet suggest using a 12mm flex socket, but being cheap I used a separate socket and u-joint so that I would have a more useful general purpose tool left over than the 12mm flex socket (better yet, I borrowed the u-joint and saved another $8). A 3/8” u-joint is a slightly bigger animal and in my opinion would make it hard to get the socket onto the bolt. It was not at all difficult to loosen the bolt using this setup. I had also borrowed a 16” extension and found it very difficult to get the socket onto the bolt head (I gave up after about 2 minutes, so it probably could have been done).
Once the bolt was out, I used a magnetic pickup to retrieve it (and eliminate the possibility of dropping it into the engine cavity where as you will find out soon, is not a very friendly place). With the bolt removed, you can pull the knock sensor out of the cavity by the harness and replace it. Next, I put the bolt into the new KS and used a small piece of tape to hold it in place while I stuffed it back into the engine cavity (again to eliminate the chance of dropping it in there).
Now the difficult part: I don’t see how you can locate the bolt into the hole and tighten it without stuffing your hand under the manifold. Others have reported that they used a claw type pickup to reposition the bolt in the KS, get the bolt started in the hole and then use the socket extension to tighten the bolt down.
If you have very large hands, you might try enlisting a girlfriend, your mom or a small child as others have done. I was able to get my hand in there and get the bolt hand tight, then it was just a matter of using the 9” extension/u-joint setup again to do the final tightening. Your hands will get cut up a little doing this, but no worse than I am used to with other auto repairs.
I was able to replace the KS in both cars in less than 1 hour including test drives using this method. The real key is using the skippynet socket extension method to crack the bolt loose. Once you have jammed your hand into the engine cavity you will realize how difficult it would have been to get a wrench on the bolt and loosen it.
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