I am not sure what to do. The knock sensor code has come up a few times after clearing it. I have recently, within the last yr, replaced the OXY sensor and MAF. The car seems to drive fine, but i don't want to take the chance and have the engine blow/burn out, whatever can happen. When i turn the car on the engine seems to rattle but calms as i continue to drive, but it has done this for a while. The knock sensor has only come up last 2 months. It will cost me 300 to replace it and i can afford it, but do i need to do it? I have been hit fixing a lot on this car within the last yr, but i want it to last a few more yrs if possible. I only have 90k miles on it. Any advice would be great. Thank you for taking the time to look and comment.

The knock sensor will not turn on your check enging light and will not cause any other component to fail. Its completely up to you if you want to replace it. For $300 on a 97 altima, I wouldn't

pm_page6776 wrote:The knock sensor will not turn on your check engine light

It most certainly will.

To the OP:

The knock sensor will throw a fault code of PO325-PO329 in your car. You may also have another contributing code with this. Possibly the MAF, EGR valve, or O2 Sensor. These component failures will sometimes cause your car to run abruptly. This will also trip your knock sensor, many of the times. My advice, is to leave the knock sensor alone.

The only time you should replace your knock sensor is if your ECU is reporting a knock sensor code only, and only after clearing the knock code several times should you consider changing it. The knock code gets thrown along side other codes very often.

The knock sensor is important if your have a major problem with your car. Major misfires, timing, etc. These things will grenade your engine. If your engine is running smooth, then I wouldn't worry about the knock sensor. However, If its running rough and sputtering, I would look into the fix. Remember, the knock sensor only lets you know there is a problem somewhere else in the car. It not the problem itself

Thank you very much for the replies and the good information. In the 97 altima the check engine light doesn't come on with the knock sensor, i only knew it because when someone scanned it that is when i knew. I am not sure about what misfires are, timing, but i believe my car is runnig OK. The knock code has been the only code popping up last month+ but my car seems to be running the same way it has for a while now. Any further information would be great. Thank you everyone.

With all due respect adidas, the P0325 code is set due to a faulty knock sensor and IS the reason for the code and will NOT cause a driveability issue other than spark knock due to the ecm not receiving a signal from the sensor to retard the ignition timing. If you have excessive spark knock, I agree, other factors are likely the cause (most likely a vacuum leak or a mass airflow sensor causing a high airflow alpha reading ) As far as the knock sensor causing the light to come on, a P0325 code will NOT cause the light to come on. it is functionality code indicating a circuit malfunction 99% of the time due to an open in the sensor itself. Not only will it not turn the light on but will pass emissions testing here in Atlanta. Don't believe me? try unplugging the sensor and you will see.

johnjohn4 wrote: When i turn the car on the engine seems to rattle but calms as i continue to drive, .

this is unrelated to your ks, but needs to be addressed.why does it knock?is you oil pan bent up, obstructing the pickup tube?have you removed the superfluous upper chain guide?ka24de are pretty hardy, but as with any engine owner abuse can kill it.

You can fight me all your want, however, to say the knock sensor will not throw a fault code is absolutely wrong. If you don't think a PO325 code will throw the SES light, you should read up a bit, or even try google. I bet you find many testimonials of people getting SES lights with the PO325 code as the culprit

You are obviously very intelligent, but I still disagree. I have read up (more than a bit) check my occupation. I did not say it would not throw a fault code. P0325 is a fault code. I said the code would not trigger a light. And I am not going by online testimonials. I am going by Nissan factory training and experience. And nevermind about unplugging the sensor, with your VQ you will never reach it. If you want I will unplug my QR sensor and report back to you. I have a Consult 3 so clearing the fault will not be an issue for me. I have no problem admitting when I am wrong.

P.S. my QR is jealous of your VQ

Sorry, Im and aircraft comp tech. A fault code is a term we use for a displayed indication of a fault. Im sorry If I insulted your intelligence. Your knowledge on this forum will be most helpful I would still be in shock to think a knock sensor malfunction wouldn't trigger a light. I use online resources a lot because, people wouldn't post questions like " I got an SES light with a PO325 code????" If that really didn't happen to them

A P0325 will set a engine light in other makes of vehicles from what I understand. And to tell you the truth, I don't know about codes other than P0325. The only knock sensor codes I have ever seen in nissans is the P0325 due to an open circuit in the sensor itself. Why nissan designed it to be this way I could not tell you (I thought it was federally mandated being an OBDII code). Haven't had the chance to try our little experiment yet but will get back to you. Have to hook up the scanner soon anyways to initialize my tire pressure sensors.

I wish you lived in socal with the consult III. It would be most helpful for my turbo build