# knock sensor and 02 sensor code



## black96SE-R (Sep 11, 2004)

would anybody have any suggestions for why my car is throwing a knock sensor code and rear o2 sensor code. before i go out and buy both parts. both codes came on at the same time. and since these codes have went on i get bad gas mileage and acceleration problems. im pretty sure the gas is cause the o2 sensor but would the knock sensor give me acceleration problems too. ill accelerate and the rpms will go up but the speed will increase slowly then itll kick in and accelerate like normal. would anybody know how i change the rear o2 sensor if i do need one. the sensor comes from the cat the the wire just goes into the underneath of my car. were doesw it go and how do i unclipp it if i cant see the other end. and were is the kncok sensor. p.s i havea 96 200 se-r


----------



## RedHead7 (May 30, 2006)

This is really weird, I have the same EXACT problem. Have you figured anything out yet? I'm trying to figure out what to do, I do not want to spend $90 on a knock sensor and another $60 on a rear O2 sensor. Please lend me some insight on this problem, I want my power back!


----------



## Burn 17 (Dec 1, 2004)

clear the codes and then see if, and when they pop back up, then you can maby figure out some of the problem


----------



## captain_shrapnel (Sep 10, 2004)

Yes, knock sensor will screw with acceleration. When it senses knocking, the ecu dials down timing and richens the mixture to stop detonation.


----------



## 200sx sEEarrh (Sep 18, 2006)

black96SE-R said:


> would anybody have any suggestions for why my car is throwing a knock sensor code and rear o2 sensor code. before i go out and buy both parts. both codes came on at the same time. and since these codes have went on i get bad gas mileage and acceleration problems. im pretty sure the gas is cause the o2 sensor but would the knock sensor give me acceleration problems too. ill accelerate and the rpms will go up but the speed will increase slowly then itll kick in and accelerate like normal. would anybody know how i change the rear o2 sensor if i do need one. the sensor comes from the cat the the wire just goes into the underneath of my car. were doesw it go and how do i unclipp it if i cant see the other end. and were is the kncok sensor. p.s i havea 96 200 se-r


as others have said, first reset your ECU.

If codes still come back on, get a new o2 sensor. Reset codes a few times again.

hopefully knock sensor code will be gone, but if it's still there then you need a new knock sensor.

sometimes the o2 sensor will throw a code in tandem with the knock sensor for no reason.


----------



## RedHead7 (May 30, 2006)

I reset the ecu after I checked the codes, and then it came on again the next day. I will probably need a new O2 sensor. I will see if it is still on after I get my new cat though.


----------



## zero1dhd (Aug 22, 2006)

as for the knock sensor - check to see if it is tightened to the FSM torque specs. (I used to have problems w/ my knock sensor and I looked at it and the thing was really loose - the bolt had almost fallen out)
as for the O2 sensor - if you reset the computer and it keeps throwing CEL's, something is obviously wrong w/ it. If I remember correctly, you're looking at a lifespan of about 100K miles for an O2 sensor, so if you're around that milage - it's probably that time. If not, you may want to check all the wires and such to make sure everything is looking good. The lower O2 sensor does sit towards the bottom of the car, so if you're driving off-road or something it is possible for a rock to kick up and smash the O2 sensor.
To unplug the O2 sensor, first locate it, then follow the wires up (about a foot) and there will be a plug, push in the lock clip and unplug the sensor, then you can easily unscrew the sensor w/ a little penetrating oil (or WD40)
The knock sensor is located on the back side of the motor, a little to the drivers side of the oil filter, and I think up a little (it's the only sensor sitting back there) it has 1 or 2 wires going into what looks like a big plastic washer w/ a bolt running thru it.


----------



## RedHead7 (May 30, 2006)

Where is the knock sensor located on the car, I have looked, but cannot find it.


----------



## DreSEL (Aug 28, 2003)

RedHead7 said:


> Where is the knock sensor located on the car, I have looked, but cannot find it.


The best way to get to it is from under the car. It is located on the back of the engine, facing the firewall, under the intake manifold.


----------



## RedHead7 (May 30, 2006)

Alright thanks, I will take a look under the car. One more thing, what exactly does it look like??


----------



## captain_shrapnel (Sep 10, 2004)




----------



## RedHead7 (May 30, 2006)

Ok, thank you. I will look around for that. Why does it have to be so small???


----------

