Knock sensor - where is it?

Anyone have a diagram of where the knock sensor is located ('95 SE)?

It's under the intake manifold, sort of twards the right side. It's a small black module held in place by one bolt.

Found the knock sensor and changed it today. Took about 15 minutes...

Thanks.

Originally posted by PhatBastard
Found the knock sensor and changed it today. Took about 15 minutes...

Thanks.

15 Minutes? Your good! I've heard a few interesting stories from guys who've changed them.

Did you notice any improvement in performance yet?

Well,I didn't include the 2 days of contemplation on what was the best way to go about it.

But after reading a couple of posts here and on the "Org", I came up with a solution that works - and works fast!

I documented the proceedure on a personal website of mine that I mess around with from time to time. If anyone is interested. Why? Who knows. Just another hobby I guess.

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

Oh and I haven't noticed any improvement in performance as of yet. From my research, it looks like it takes a few days for any noticeable difference.

I've reset the ECU, so hopefully this will clear up the O2 sensor message as well.

Time will tell...

Why did you have to replace your knock sensor, cause my ecu is throwing a knock sensor code also. One more thing. how do you gain performance by replacing the sensor?

LMAO, nice website write-up !!
I loosened the nut a bit different, and was careful of banging my hand when it came loose, because I knew what would happen :D


You will not gain any "performance". the only thing is your engine will not knock anymore if you use low octane gas.

when you use low octane gasoline the knock sensor retards the timing in order to prevent the "knocking" of your engine in which you might "feel" a decrease in "performance".

so from now on use 93 octane gasoline :)

Originally posted by maxgtr
Why did you have to replace your knock sensor, cause my ecu is throwing a knock sensor code also. One more thing. how do you gain performance by replacing the sensor?

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My ECU was spewing the knock sensor code and a rear o2 sensor code.

Under advisement of NJMAX, I replaced the knock sensor first, in hopes that it would also clear up the o2 sensor message. So far, so good.

The check engine light has not come back on. If it doesn't come back on in the next couple of days, I'll be satisfied that both conditions have been corrected.

As far as better performance, I can't say. I've seen many opinions on this, some saying it will, some saying it won't.

My question is, if the knock sensor is bad, does the ecu still retard the engine? If it does, then maybe you'll see better performance. If not, then nothing should change. Ya think?

My next question is, why does the little bastard cost so much? A plastic doughnut with a metal bottom. Give me a break....

Originally posted by MaxRX7
LMAO, nice website write-up !!
I loosened the nut a bit different, and was careful of banging my hand when it came loose, because I knew what would happen :D


You will not gain any "performance". the only thing is your engine will not knock anymore if you use low octane gas.

when you use low octane gasoline the knock sensor retards the timing in order to prevent the "knocking" of your engine in which you might "feel" a decrease in "performance".

so from now on use 93 octane gasoline :)

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Glad you liked it!

I just started using 92+ octane a couple of weeks a go thanks to information that I read here and on the "ORGY". I have been running the the middle grade (usually about 89) for all of these years because I swear on my granny's grave that the salesman told me to use the middle grade of gas back when I bought my Max new in May of '94, the rat bastard!

PhatBastard, your page is definitely the best thing going out there for KS replacement. Got the tools you suggested but when I went to loosen the screw, the damn thing just would not budge. The car was still kind of hot so maybe when cold, it'll be easier. I also sprayed some liquid wrench on it.

I too would like a definitive answer as to whether timing is retarded (or not) when the KS is bad. I get 0304 code but subjectively, I still feel like my car has good acceleration! We'll see when I change it out...

As for mid-grade: it isn't necessarily a bad thing. The KS is supposed to retard the timing so that no knocking occurs. It is not supposed to damage the KS... Even the manual says that if premium is not availble, "plus" grade will do. You just won't get optimal performance.

Update: With the car cold and the bolt sprayed with liquid wrench, all it took was a good yank and the bolt came loose. Just kept turning the socket until it was out and held the bolt with a magnet antenna. Didn't even have to stick my hand in for the removal portion!

Glad my web page helped and your idea with the magnet is excellent.

I'll update the web page with your ideas when I return home later this week (I'm working in Atlanta for a few days).

Thanks for the info on the mid grade as well. I don't feel so guilty now!!

I'll try to remember to let you know when I update the web page.

Later.....

Originally posted by PhatBastard


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Glad you liked it!

I just started using 92+ octane a couple of weeks a go thanks to information that I read here and on the "ORGY". I have been running the the middle grade (usually about 89) for all of these years because I swear on my granny's grave that the salesman told me to use the middle grade of gas back when I bought my Max new in May of '94, the rat bastard!


NEVER, ever listen to a salesman !!
Whenever you get a new car, read the manual, this is by far the most important thing. It clearly states to use premium gasoline.


BTW, how much did the knock sensor cost you ?

I paid $164 & change for the sensor from Courtesy. I saw some that cost less and some that cost more. Saw a couple of different mfgs. too.

I went wth the middle of the road (cost wise) from a reliable source.

Am wondering if anyone has done the continuity test on their knock sensor as per Haynes Manual. Test: check the resistance of the KS. If it is infinity (no continuity), then they say to replace it. They do say that the KS has a high resistance and recommend an OHM meter with at least 10M Ohm capability.

If you do try to do this, you cannot just measure at the harness because only one of the leads (the signal one) actually goes to the KS. The case of the KS is grounded so you will have to measure with the terminals of the KS that you took out, or use the hot lead of the harness and use the ground of the car.

Well, because my new KS will take a couple of weeks to arrive, I decide to play with the dead old one. On my multimeter, the resistance at the terminals of the sensor itself is infinity (no continuity). Fine, it's dead. Code 0304 told me that (no CEL). Even clearing the ECU would not make the 0304 disappear.

Noticed that the metal bottom of the KS was tarnished/rusted. Also noted a crack to the plastic casing near the terminals with some metal visible. Decide to sand dremel the bottom and put some Automotive Goop sealer to the crack. Well today when I go to measure the resistance, I get a number! It varies continuously from about 14-16 M Ohms. On my multimeter, the KS has polarity. Measuring in one direction, I get no continuity and switching the leads, I get the 14-15 numbers... Putting the KS back in and resetting the ECU, I get NO CODE. I drive around, and maybe it's all psychological, but I feel like the pedal is more sensitive, ie. more power. I know the bottom rust has nothing to do with it but could sealing that crack in the casing do something? It doesn't make sense but my KS is now working (seemingly) and doesn't put up a 0304.

I'm still going to swap in my new KS when I get it but I may just apply Automotive Goop to the top casing to strengthen it...

The CEL came back on today with a 7-7. So, replacing the KS didn't clear up the O2 sensor problem like I had hoped.

I've ordered a new O2 sensor ($82 @ thepartsbin.com).

Also, no noticeable performance gains from replacing the KS.

The CEL came back on today with a 7-7. So, replacing the KS didn't clear up the O2 sensor problem like I had hoped.

I've ordered a new O2 sensor ($82 @ thepartsbin.com).

Also, no noticeable performance gains from replacing the KS.


phatbasard: could you make a page on your site for how to change the rear O2 sensor? i have the same problem. I took it to autozone and they said ks and rear O2 are messed up. they also told me to get trouble shoot before replacing parts, what's that? let me know if ur O2 makes CEL go away.

CEL does not come on when the KS trips. Usually, what happens is an O2 sensor goes out and causes the KS code. Change your O2 before the knock sensor. Here's how:

Upstream O2 sensors:

Necessary tools:

*3/8" drive ratchet
*16mm O2 sensor removal ratchet (rent it from Autozone for free)
*OEM upstream O2 sensor(s)
*Anti-seize
*PB Blaster (or WD40)
*Scissors

1. Put the front end of the car on ramps or jackstands
2. Spray the O2 sensors with PB blaster (or other lubricant) to make removal easier; wait ten minutes.
3. Using the O2 sensor ratchet attachment, loosen the current O2 sensors that are installed in the "Y" portion of the Y-pipe
4. Trace the sensor harness up to the engine bay and unplug it. One will be close to the cabin, to the left of the spark plugs; the other will be clipped by the radiator, towards the front of the car
5. Cut the plastic things holding the harness; there will be multiple ones
6. Completely unscrew the O2 sensors
7. Plug in the new sensors to the now-empty connectors that the old sensors were attached to
8. Dangle the sensor from the engine bay to the underbody of the car, taking care to do it SLOWLY so you don't damage the sensor
9. Put a little anti-seize on the threads of the sensors (if there isn’t any already)
10. Screw 'em in and you're done.

Downstream O2 sensor:

Necessary tools:

*12mm wrench
*OEM downstream O2 sensor
*Anti-seize
*PB Blaster (or WD40)
*Scissors

1. Put the rear end of the car on ramps or jackstands
2. Locate the downstream O2 sensor; it is in rear-half the catalytic converter, on the driver’s side (middle of the car is where you should be looking)
3. Spray the sensor with PB Blaster or WD40
4. Trace the harness to the underbody of the car
5. Pull on the harness until the rubber seal pops free
6. Disconnect the old sensor from the harness
7. Apply anti-seize to the new O2 sensor (if it doesn’t already have some); take care not to get the compound on the sensor head
8. Screw in the sensor
9. Connect the new sensor to the harness
10. Jam the excess wiring back into the hole and close it up with the rubber seal
11. Using one of the supplied zip ties, secure any slack wiring.

~THT

CEL does not come on when the KS trips. Usually, what happens is an O2 sensor goes out and causes the KS code. Change your O2 before the knock sensor. Here's how:

Downstream O2 sensor:

Necessary tools:

*12mm wrench
*OEM downstream O2 sensor
*Anti-seize
*PB Blaster (or WD40)
*Scissors

1. Put the rear end of the car on ramps or jackstands
2. Locate the downstream O2 sensor; it is in rear-half the catalytic converter, on the driver’s side (middle of the car is where you should be looking)
3. Spray the sensor with PB Blaster or WD40
4. Trace the harness to the underbody of the car
5. Pull on the harness until the rubber seal pops free
6. Disconnect the old sensor from the harness
7. Apply anti-seize to the new O2 sensor (if it doesn’t already have some); take care not to get the compound on the sensor head
8. Screw in the sensor
9. Connect the new sensor to the harness
10. Jam the excess wiring back into the hole and close it up with the rubber seal
11. Using one of the supplied zip ties, secure any slack wiring.

~THT


thanks for the info, appreciate it. in another subject in this forum this is what they said about changing the rear O2.

go under the car. its a 22m bolt head. there should be a plastic covering under the car, pop that off and the rear o2sensor cables should be there, and just unclip and replace with a new one.

it's from this link - http://www.automotiveforums.com/t31933.html

Cheston knows his stuff (think he drives a TT 350Z now) but it's a little vague. And it's definitely a 12mm that you need. Good luck. It's very easy to do; before I did mine for the first time, the most I had done to my car was change the oil.

~THT

Does the 91 Maxima have (2) o2 sensors as well? I am getting the detonations sensor error & the "Org" suggested replacing the o2 first

Wish I could tell you but most of my knowledge is 4th gen related.

~THT

Does the 91 Maxima have (2) o2 sensors as well? I am getting the detonations sensor error & the "Org" suggested replacing the o2 first


THT what percent tint is that? I'm thinking of tinting my windows. I think I want it darker than yours are. Is there a picture site that shows you how to tint the them? ...kind of like phatbastards knock sensor page.

I don't know as I didn't put it on the car; previous owner did it. I plan to go with 20% all around soon.

~THT

Would not have found the KS without you folks. Thanks much.

My service light came on yesterday. Autozone hooked up to it and identified the KS and Bank1 O2 sensor. Can anyone confirm that replacing the O2 sensor might eliminate the KS code? I'm told that if the KS is really bad, that it could mess up the engine pretty good by firing the ignition "off sequence". So if the risk is high, I don't want to chance not replacing the KS.

Thanks for the help.

THT what percent tint is that? I'm thinking of tinting my windows. I think I want it darker than yours are. Is there a picture site that shows you how to tint the them? ...kind of like phatbastards knock sensor page.

judging by the picture...it looks to me as if his tint is 80%...most of the tint like that is

judging by the picture...it looks to me as if his tint is 80%...most of the tint like that is

Thanks for the input. I checked ohio law and it says i can have 30% in the front and any % in the back. So i'll be going with 20% in the back.

slyprince:

you can try resetting the check engine light and see if that makes it go away. I was going to do that but tomorrow i'm taking mine to my mechanic he's going to check it. his pc can tell which gave the light first (O2 or KS). I think I will reset it and see if it comes back on or not because it drives fine with no problems or loss of gas mileage.

Yes, four out of five times your KS trips, it's because of a failing O2. Change your O2 first, reset your ECU and check for any codes.

~THT

I reset my ECU and now no CEL. It's been three days now. First it was giving me the code for O2 and KS but after resetting it it's all gone. I think my engine oil was kind of low so that might have triggered it.

Now I'm planning on fixing my clock. It doesn't work. Anyone knows how I can open the panel to take the clock out? and also the knob that makes the side mirrors move.

I ended up replacing both the KS and O2 sensor. Seems to run a little smoother. The service engine indicator went off by itself 2 days later.

Sorry... I can't help with the clock. I haven't had to tear into the dash yet.

I was going to reset my ECU & then decide if I should change any sensors. Thursday I noticed that may Max didn't give me any trouble! I looked at the gas gauge & noticed I was on empty. That was the first premium tank I bought in 2 years and that must have helped.
It's been four days and I think the problem went away. The only thing I did was run premium gas ( 1 full tank) and some gas treatment & fuel injector cleaner - after the full tuneup w/ fuel & gas filter didn't fix the problem.
I think I will alternate mid grade to super & see if that keeps the problem from returning.

Stick with one grade as alternating is bad for your catalytic converter.

~THT

I can't afford $120 bucks a month in gas. I guesse I'll go middle of the road. Any feedback?

Drive less aggressively and run the good stuff. It's better for your engine. You don't want knock issues when you've got a lot of miles on your engine.

~THT

for some reason your instruction link will not work on my computer. have your disable this link? and if so please let me know. thanks a million!

Anyone have a diagram of where the knock sensor is located ('95 SE)???????

How To Bypass (see 5c method - works for 'any' model): http://www.cardomain.com/ride/748507/9

...where /KS location: check suggested links for your model