Nissan XTerra Forum banner

1 - 20 of 226 Posts

·
Silver Submarine
Joined
·
10,979 Posts
Discussion Starter #1 (Edited)
I'm gonna make this a sticky cause its just talked about so much and recently there has been new information on this topic. If you are getting a PO328/P0325 code on your truck it is the knock sensor and it probably has gone bad but there are other possible reasons for getting the code. You might have gotten a bad tank of gas or your ignition system isn't working as good as it should. I would recommend you fill your tank with hi octane gas or gas treatment, run through that tank and check for the KS code again after you have cleared it and do other repairs before attempting the knock sensor replacement or by pass. Make sure your ignition system is working as it should. If after you have do all that and you are still getting the KS code your KS or harness might be bad. Its your choice to to do the replacement or by pass. We are trying to give you all the information we can to help you in your decision. There is not one good answer for your decision. Some decide to do the replacement. Some decide to do the by pass and some decide to leave it alone. Again the choice is yours!

It seems as though when your knock sensor goes bad the ECM will retard the timing to a preset position in order to prevent your motor from "knocking or pinging". This retard in timing will possibly reduce power and you will get slightly less MPG's but probably not enough to notice in the NA 3.3. In the supercharged 3.3 the ECM will put the truck in "limp" mode and you will notice a major reduction in power. This is to prevent your 3.3 from destroying itself. By doing the knock sensor by-pass you have now removed the safety from the system and will have to be diligent in what type of fuel you run and your driving habits. The knock sensor is attached to the cylinder block. It senses engine knocking using a piezoelectric element. A knocking vibration from the cylinder block is sensed as vibrational pressure. This pressure is converted into a voltage signal and sent to the ECM. Freeze frame data will not be stored in the ECM for the knock sensor. The MIL will not light for knock sensor malfunction. The knock sensor has one trip detection logic.




#1. Bad knock sensor won't set an SES light. The code was already there when the light came on.
#2. Bad knock sensor will possibly decrease fuel economy.
#3. Bad knock sensor will Possibly retard timing causing a slight reduction in performance but probably not enough to notice without monitoring live data.
#4. Knock sensor bypass should be done at your own risk especially with a SC Xterra.

The red arrow points to the location of the knock sensor:
 

·
Registered
Joined
·
2,003 Posts
Couple things to add:

1. Do not do anything if you get the code once, it could be a bad tank of gas, impurities whatever. Fill up again and half way through take it to a autoparts place and have them pull the codes again (most will for free). If it remains, do it again at another tank. Give it a few tanks before considering anything.

2. Once you are certain that its bad you have a few options:

Get it repaired
Pros: It put your engine back in to correct working order
Cons: EXPENSIVE repair, quotes have been in the $750-$1500 range

Leave it
Pros: You don't have to do anything
Cons: Your engine may not perform at its peak and you may be costing yourself some gas milage (how much varies)

Relocation mod
Pros: Moves it to a much more easily accessible spot, cost is much cheaper then replacement ($200 using OEM parts), your engine has knock protection again
Cons: Not in the factory location, not as accurate.

Bypass mod (not recommended for SC engines)
Pros: Regains timing and milage lost from bad sensor, very cheap
Cons: You now no longer have ANY knock prevention, could lead to engine damage but unlikely.
 

·
Registered
Joined
·
760 Posts
Thanks for the pro/con report. I almost feel like I SHOULD do it the right way. My luck, "cheating the system" will wind up with a major fk up later on. lol
 

·
Administrator
Joined
·
8,748 Posts
Thanks for the pro/con report. I almost feel like I SHOULD do it the right way. My luck, "cheating the system" will wind up with a major fk up later on. lol
If your NA truck is throwing a KS code you're not cheating the system as it is already retarding the timing to prevent knock.
 

·
Registered
Joined
·
760 Posts
Sorry, by -cheating the system- I meant would be to Reposition the KS and not Replace it where it belongs under the manifold.
 

·
It was always fumbles
Joined
·
13,000 Posts
For noobs don't not freak out..

We seem to get some new people on here that read a few lines of a topic then become that guy that has all the answers.. Make up your mind on this topic.. Please read up on this topic as much as you can and go from there
 

·
Registered
Joined
·
10 Posts
Question: Recently my car when it is idle shakes/vibrates it is subtle and almost seems like it is running out of gas (but it has a full tank) I've been putting STP stuff in my xterra but it doesn't seem to make a diff. Friday I got the CEL and the two codes that came up are 450 and 325. I tried to find the knock sensor but I can't find it in my car. I freak out when something is wrong with my car and I don't like the vibration thing it is doing. Help =/
 

·
Registered
Joined
·
760 Posts
The knock sensor is locate under the plenum on the top of the engine. From what I've read, it's anywhere from 6-10hr job.
 

·
Registered
Joined
·
57 Posts
Couple things to add:


Bypass mod (not recommended for SC engines)
Pros: Regains timing and milage lost from bad sensor, very cheap
Cons: You now no longer have ANY knock prevention, could lead to engine damage but unlikely.
curious as to why you say NOT RECOMMENDED FOR S/C ENGINES? the person who has the DIY write-up on this site is doing it to a S/C engine and sounds like it worked just fine. i'm not saying your wrong - you may be spot on, which is why i'm asking. i have a S/C and am considering doing this mod. i paid to have the dealership replace the original and it made a HUGE difference, for sure, but i still think it's robbing the S/C at times even still, so it would be nice to just make that thing go away. and i ALWAYS use premium fuel (at least 93 octane).
 

·
Premium Member
Joined
·
140 Posts
x2 mattyg.. i have the 03 SC an always use premium... id like more info on the mod because i really dont wanna drop major coin on something thats gonna pop up in the next 50k miles anyways an is a bitch to get to
 

·
Registered
Joined
·
204 Posts
it looks like the KS is between the back two cylinders on the right side (passanger side) in the picture. Is it nessecery to remove all that is missing in the picture to access the KS? Also, is it possable the a bad bearing in the Distributor shaft will throw the KS code? I get about 16-19 mpg is that average (I have a lead foot and the non-SC has little juevos.) I always thought 17 mpg was pretty good considering I average 75-80 mph when I travel.
 

·
Registered
Joined
·
179 Posts
The following is from an old thread. It should help you make an informed opinion on which choice to make, and locate the wires needed to do the mod, if needed. I've been running with the resistor mod for 8+ months:

"I used the following thread from a Frontier forum to help me identify the connector and wires to solder the 560k ohm resistor. The picture, along with post #15 from that thread will help. I'll add that when I cut the plastic wire loom back about 6" on the wire bundle to the proper connector, I found the two wires we're dealing with were in thier own bundle within that loom. That left no doubt I was soldering the correct wires together with the resistor.

http://tunfs.yuku.com/topic/363/t/Kn...-or-PO327.html

I'd recommend reading the whole thread, though. People raise some valid concerns and offer reasons the relocation mod might be a better option. Well, second best to replacing the KS in its original location, that is. I'd hate for anyone to damage thier rig following my suggestions for the resistor mod."
 

·
Banned
Joined
·
642 Posts
Note: this is for a NA engine:

There's only two, the Intake Gasket and the Plenum Gasket (or Upper Intake). There may be a couple of different names for each part, but to go RockAuto.com and search part MS922704 It's the Fel-Pro set of both.

For a SC engine there is also a couple of gaskets around the SC. Check this thread http://www.clubxterra.org/forums/showthread.php?t=19977

If you're that deep in, might as well swap out the valve cover gaskets if your's is approaching the pre-teen years.
 

·
Registered
Joined
·
4 Posts
I've read a bunch about fixing this P0325 31 knock sensor problem I'm having with my 2000 nissan x terra.... replaced distributor cap, rotor, plug wires , fuel filter and cant get rid of code...
It ran really smooth at idle after new cap and rotor, plug wires - for only a short 5 minutes ...but then the knock came back and wouldn't stay running
 

·
Registered
Joined
·
5,824 Posts
I've read a bunch about fixing this P0325 31 knock sensor problem I'm having with my 2000 nissan x terra.... replaced distributor cap, rotor, plug wires , fuel filter and cant get rid of code...
It ran really smooth at idle after new cap and rotor, plug wires - for only a short 5 minutes ...but then the knock came back and wouldn't stay running
What do you mean by the knock came back? An actual engine knock or a knock sensor code?

Also if it's been a while since you did a tune up, you should replace your plugs too.
 
1 - 20 of 226 Posts
Top