Code 03 04
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Member
Joined: Apr 2003
Posts: 271
Code 03 04
My engine light is NOT on when i drive but i was reading some posts a while back that said the "Knock Sensor" will not always trigger the engine light.
I did the ecu test and i got 03 04 which the "ECU ERROR CODE DECODER" says is my Knock Sensor, now is that it? should i go and pick a new one up?
I dont want to lose a bit of "stock" performace
I did the ecu test and i got 03 04 which the "ECU ERROR CODE DECODER" says is my Knock Sensor, now is that it? should i go and pick a new one up?
I dont want to lose a bit of "stock" performace
yes u need to replace hte knock sensor, you can buy one off ebay for ur local dealer or an online dealer like www.newnissanparts.com
how to is here http://www.motorvate.ca/mvp.php
how to is here http://www.motorvate.ca/mvp.php
Member
Joined: Apr 2003
Posts: 67
I changed the KS in my wifes and my Maximas yesterday and here are some hints:
Once and for all: a bad knock sensor WILL NOT trip the check engine light, you must extract the codes from the ECU to determine if your sensor is (potentially) bad (code 0304). Some other hints as to a bad KS: poor acceleration below 3000 RPM (I was getting tired of being left behind at stoplights by Honda Civics).
If you don’t already own a Haynes or Chilton manual, get one. In addition to telling you how to extract the codes and locate the KS, there is a wealth of useful information for the do-it yourselfer. I am very cheap, but this an area well worth spending the $20 or so (I bought mine off of EBAY for $10 shipped). I am not going to encourage your cheapness by describing how to extract the codes. If you are really cheap, you can get that information elsewhere.
A good KS will measure ~550 k-Ohm resistance between the left pin of the KS and ground. You can check the resistance without removing the KS by following the harness to the connector. The connector has two pins, only one of them hooks up to the KS, so try them both. The act of whacking on the KS with your wrench can (temporarily) start it working again, so checking the KS once you removed it may not give you the bad reading you suspect. Hint: the connector is not the green one closest to the KS (1995-1996 models – most likely 1994-2000), it is a few inches closer to the front of the car. A heat shielded wire leads into the bottom of it and there are two wires coming out the top, one clear and one black.
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 (and I mean stuff). If you have very large hands, you might try enlisting a girlfriend or you mom 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. Go inside, clean up and put some disinfectant on your cuts.
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 skippyney 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.
Once and for all: a bad knock sensor WILL NOT trip the check engine light, you must extract the codes from the ECU to determine if your sensor is (potentially) bad (code 0304). Some other hints as to a bad KS: poor acceleration below 3000 RPM (I was getting tired of being left behind at stoplights by Honda Civics).
If you don’t already own a Haynes or Chilton manual, get one. In addition to telling you how to extract the codes and locate the KS, there is a wealth of useful information for the do-it yourselfer. I am very cheap, but this an area well worth spending the $20 or so (I bought mine off of EBAY for $10 shipped). I am not going to encourage your cheapness by describing how to extract the codes. If you are really cheap, you can get that information elsewhere.
A good KS will measure ~550 k-Ohm resistance between the left pin of the KS and ground. You can check the resistance without removing the KS by following the harness to the connector. The connector has two pins, only one of them hooks up to the KS, so try them both. The act of whacking on the KS with your wrench can (temporarily) start it working again, so checking the KS once you removed it may not give you the bad reading you suspect. Hint: the connector is not the green one closest to the KS (1995-1996 models – most likely 1994-2000), it is a few inches closer to the front of the car. A heat shielded wire leads into the bottom of it and there are two wires coming out the top, one clear and one black.
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 (and I mean stuff). If you have very large hands, you might try enlisting a girlfriend or you mom 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. Go inside, clean up and put some disinfectant on your cuts.
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 skippyney 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.
Senior Member
Joined: Mar 2002
Posts: 271
Actually - as per my thread in this forum "Replaced Knock Sensor - No Bloody Stump" - managed to pull it off without having to stick my hand in there. I used a claw-type pickup tool to retrieve as well as place the bolt back in the k/s after placing it in the block. as for making the bolt "catch" the thread in the block - I placed the K/S (with the bolt) slightly "before" or ahead of where I thought the hole would be and then got the 12 mm socket (with the U-joint / extension and all) and while putting slight downward pressure on the bolt genlty slid the entire K/S (and bolt) and the bottom of the bolt "sat" itself on the thread cavity. The depth of my 12mm socket is shallower than the length of the K/S bold when it is not threaded into the block (if this makes any sense) - so it is very easy to push down on the bolt because of this and slide it forward till it seats itself in the hole.
Getting some light in there helps and I found the best way to do this is to have someone else hold a flashlight for you. When you are in your "Knock Sensor Removal position" (looking over the left fender into the valley of the "V") move slightly to your left and have your buddy flash the light over your right shoulder and move your right arm out of the path of the light. Having the area lit helped tremendously. Once I cracked the bolt loose (use WD-40 and let it sit for a few minutes, mine were factory-torqued to hell) - the rest of the procedure I felt was highly overrated. My advise is be very patient with the whole process. From cracking the bolt loose to finishing up and shutting the hood took no longer than 15-20 minutes and that included putting the airbox back (which I removed for better access - but didn't make much of a difference).
Good Luck!
Getting some light in there helps and I found the best way to do this is to have someone else hold a flashlight for you. When you are in your "Knock Sensor Removal position" (looking over the left fender into the valley of the "V") move slightly to your left and have your buddy flash the light over your right shoulder and move your right arm out of the path of the light. Having the area lit helped tremendously. Once I cracked the bolt loose (use WD-40 and let it sit for a few minutes, mine were factory-torqued to hell) - the rest of the procedure I felt was highly overrated. My advise is be very patient with the whole process. From cracking the bolt loose to finishing up and shutting the hood took no longer than 15-20 minutes and that included putting the airbox back (which I removed for better access - but didn't make much of a difference).
Good Luck!
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Kyle Lee Cleveland
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