Good afternoon everybody,

Well I was getting the ol 0304 code (nothing but that code) so I replaced the Knock Sensor. Drove around for a couple of days and decided I would check the ECU for codes, ya know make sure the knock sensor code was gone.

Well I checked, and what the hell? I'm still getting the 0304 code....

Not really sure what to do here, don't wanna waste even more money on pointless check ups, any advice here would be very helpful. Thanks a lot eveybody.

- Steve

 

Reset the ecu and try checking it again in like a week.

 

i have said this 50 million times.. the Knock Sensor never triggers a CEL.. it usually pops up when something else is wrong..

so what do we have here? whatever it is that tripped your Knock Sensor is still broken.. and you have wasted your time and money buying a Knock Sensor

 

Just another question, the screw for my ECU is quite stubborn it only turns like a couple MM then stops both ways, then sometimes after awhile of working at it and then leaving it alone it moves, but after moving it all the way it stops at that new position, is there a trick to the ECU screw I don't know about?

- Steve

 

No trick, turn but it takes me about 1.5 turns back and worth.

 

I know that.

[/B][/QUOTE]
I was under the impression knock sensors can go bad, usually around 60K. And would that not lead to the ECU giving me 0304. So I replaced the knock.

- Steve

 

I was under the impression knock sensors can go bad, usually around 60K. And would that not lead to the ECU giving me 0304. So I replaced the knock.

- Steve [/B][/QUOTE]


no what usually happens is the 02 sensor will go at 60k.. and have a 0304 code along with the 02 sensor code..

unless you have taken the Knock Sensor off and tested the voltage.. or have a mechanic test it.. i woudln't replace it.. at $180 a part.. thats an expensive thing when it doesn't need to be replaced..

what i would do is keep resetting it until the other code pops up..

 

no what usually happens is the 02 sensor will go at 60k.. and have a 0304 code along with the 02 sensor code..

unless you have taken the Knock Sensor off and tested the voltage.. or have a mechanic test it.. i woudln't replace it.. at $180 a part.. thats an expensive thing when it doesn't need to be replaced..

what i would do is keep resetting it until the other code pops up.. [/B][/QUOTE]

I replaced an o2 sensor about 1k KMs ago. When that happened it came up with two codes one for the knock and one for the O2 sensor. I just naturally assumed that another code would have come up with the 0304 I got.

I also already replaced my Knock and am still getting 0304.

- Steve

 

sorry if i sound a bit harsh.. but typing the same thing over and over sometimes get to a person.. sorry..

i would just reset it at this point and wait or it to pop up again..

 

Ok. I have a 0304 code too, and i dont feel like throwing away money for no reason. So how do you find out what is ACTUALLY broken?
And why do i need to take the knock sensor to a mechanic to test it? I thought we could check the resistance and if it was within the 550kohm range it was fine and doesn't need to be changed...

 

 

ignore the red line

 

I'll second that.

Great info from the FSM Sprinty..

 

while sprintmax is usually right, in my case, i did have a bad KS, and it was the ONLY code pulled and my car had all the signs of a bad KS, bad mileage, intermitant acceleration etc. and when i pulled it out, it tested totally open, so yes, knock sensors do go bad. and make sure you reset the ECU (just the CEL light reset, even if you dont have a CEL) after you put the new one in.

 

I replaced my knock sensor awhile ago. I had the KS ghost code (No CEL but 0304 was the only code stored in the ECU). After I replaced the faulty KS with the new one I reset the ECU. I checked for codes and the CEL blinked 0505.

I just checked the ECU this morning and its still 0505.

 

That is an important point. When I first changed the sensor, it still came up 0304. After I reset the ECU, it was 0505 and the KS code never came back again... You need to reset the ECU after replacement.

 

Thanks a lot buddy, thats just what I was waiting to see. I'll reset the CEL and see how that goes.

- Steve

 

See Sprinty? The knock sensor CAN go faulty by itself(remember we had a little tiff about this a few months ago)"rolleyes". While in alot of cases sprint is right the 0304 code can be caused by a faulty o2 sensor the knock sensor can go as well just like any electrical part. I had the same problems as miasma here and I changed the knock sensor....problem solved and no more codes.

 

Sprint said that KS will not trip the light by itself. Another culprit will trip the light, and often, it will cause a false 0304 code to come with it.

You can get the 0304 code, by itself, without the CEL light. Then it's usually time to get that new KS.

 

Thats is what I am unsure about because I have had a code for the vehicle speed sensor, so I have no idea if the code will come on by itself.

 

thanks

i am sorry guys if you have a bad Knock Sensor and i suggested waiting it out.. its just that the knock sensor is a $180 part.. and i would rather be wrong in an instance than have someone spend $180 on a part for no reason.. and be 100% sure its the KS.. for god sakes... you can buy a y pipe for cheaper than a KS these days..

Knock Sensors do go bad.. but are expensive to replace.. its best to be 100% sure thats the problem..

so if anyone reads this.. please don't think i am saying knock sensors never go bad.. they do.. but they will never trip the CEL .. and often times it shows up in a code when its not bad at all..

 

Is there website that tells what parts will trip a CEL and what won't?

Because I've read that some people get CEL's when their r/l heated 02 sensors are bad others don't. I am just wondering if this confusion applies to other sensors.

Thanks
Tac

 

no..

however if your 02 sensors go bad.. it will not trip the light immediately.. it takes some time.. maybe a week before it trips..

 

Mine have been damaged for a while, and no CEL.

 

I am getting the 0304 ECU code also, and the CEL hasn't turned on. Since I don't want to spend the $120-180 on a KS without knowing absolutely sure I need one, what is the best way of testing the KS? Are people removing the sensor from the car, testing it, and then going out and buying the new one, or is there a way to test it while it is still in the car?

I thought you have to disconnect the harness and then measure the resistance to ground. This would require the KS still being mouted. Then how do you remove the harness without removing the KS?

Any advice would be appreciated.

 

how do you know that they have been damaged? no cel, but the codes come up when you check?

 

hi, i remove the old KS like 1 week ago and man, what a difference, 22 mpg again!!!!!! after 16mpg, well is very important to see if the KS is bad or good. Mine was broke in 4 parts

My mechanic(who is the boss for Nissan) told me, after you reset the ECU and the codes pulls again(after the problem was fix) you should go to the dealer or find out who has a SCAN NISSAN TOOL i dont know why but just that TOOL can erase the memory of the ECU, of course if you do the normal process will erase too, but the ECU has a secondary memory that just erase all past codes with the scan nissan tool. Is like emergency memory safe. But is very rare after fix the problem have the codes again.

 

Someone mentioned 02 sensors. If you can run the ecu diagnostics to verify the 02 is cycling between lean/rich (ie.. working okay). Do that as it doesn't cost $. Also maybe test clean the KS harness connector and check that on an OHM/voltmeter.

 

Ok, so I decided to do a diagnosis even though I had no CEL about 3 weeks ago. It showed ONLY the knock sensor 0403 code. So i reset the ecu. About a week later, the bloody CEL came on. Did the self diagnosis and got the 0403 code AND a 0201 code. (I did not get the 0201 code the first time i did the diagnosis. I reset the ECU and the next day the CEL came on. Did a diagnosis which showed both the 0201 and 0403. We pulled the KS out and did a resistance test to see that it was around the 550ohms as specified. The resistance was approx 1000, so i changed the KS to another used one my mechanic (bro-in-law)had which was verified to be in working order. Reset the ecu and i was happily driving for a week now. Today on my way to work, the CEL came on. I just did a diagnosis and the 0403 code and 0201 (Primary ignition signal) both came on. What gives? WE KNOW this new (used) KS is a good one. I understand another code (in this case 0201) may trigger a KS code, but can it still trip the 0403 code even though the KS IS GOOD?? Has anyone had this combo of codes show up? Why is the KS code coming up? Why is my 0201 code coming up?!! This is driving me crazy, i've only had this car for 4 months now!!!
Any suggestions? Btw, its a 99 maxima SE auto. Thanks all!

 

Wow i wish my max got 22mpg , how much does a Knock sensor go for, does one got a pic or suttin on were its located ?

 

Wow i wish my max got 22mpg , how much does a Knock sensor go for, does one got a pic or suttin on were its located ?

 

That is code 0304 (Knock Sensor) not 0403 (Throttle Position Sensor), right?

 

In my haste to type fast, i mixed up the #'s. Yes Knock Sensor = 0304 code.

 

when stuff such as ignition coils, oxygen sensors and other sensors go.. or air in the gas tank.. it can cause the car to run lean.. or very rich.. this can offset the knock sensor code.. the engine gets a response that the car is running too rich or too lean and then automatically assumes the knock sensor is not doing its job, therefore code 0304. Once O2 sensor is fixed the car is now in prefect running order.. the engine now assumes the knock sensor is working and now the 0304 will disappear.

This is why i always urge people with KS codes to reset and try again.. and if you try it a couple times lets say for a month.. and all you get is 0304.. then you can go ahead and replace the knock sensor..

I am not sure if i am entirely accurate.. but it makes sense to me

 

i said it already in this thread