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2001 Subaru Outback, EJ253
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521 Posts
Discussion Starter · #1 ·
So I had my codes pulled when I got my car smogged so I can get my decals for base access here in San Diego, failed because I have a CEL, but it wasn't on when I was driving, the CEL has been off and on several times already. The code I have is the P0325 Knock Sensor 1 CKT Malfunction. What do I do to fix this, replace the sensor or is there more that I may have to fix?
 

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Try using a higher octane of gas . My Gf's 98 had the same code after replacing the sensor it still came back on . She started using 89 octane and the light has not come back on in months.
 

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1999 Subaru Impreza L Coupe
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281 Posts
Bringing this thread back....

About a month ago, I put a AEM SRI on my 99 2.2L... shortly after the car threw the P0325 code, a malfunctioning knock sensor... since this point, I've cleared it 3 times, and it's come back. However, sometimes (10 times maybe) it goes out on it's own.. like today it was on at 7:30am when I took my car uptown to get my golf clubs.. but at 1pm when I filled the car up the CEL shut off and has been off for 75 miles of driving....

What's that all about? I'm thinking it's a ground in the wiring and a wire is making occasional contact with the block or something?

I'm getting 33mpg on average, with winter tires still installed.. so it's running fine other than the code.


Greg
 

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2000 SRP 2.5RS Coupe
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2,164 Posts
Go to autozone, pay 70 bux for a knock sensor. Take 10 minutes swapping it out. Wa-la! No more CEL.
 

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Mobile Diagnosis Guy
97 Impreza L
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5,492 Posts
Replacing it could fix it, or it couldn't. Test the sensor and see if its good before you drop cash on a new one. Maybe it IS working and thats why you have a CEL.
 

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1999 Subaru Impreza L Coupe
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281 Posts
The description for the P0325 is a malfunctioning knock sensor, I thought that if the sensor was detecting a knock, it'd say which cylinder it came from... yes?
 

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2001 Subaru Outback, EJ253
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521 Posts
Discussion Starter · #8 ·
Well I replaced the knock sensor, I also replaced the battery at the same time, since apparently the on that I had in there wasn't the correct one to begin with, I bought the car used and the battery was a smaller one and had a lower rating and it was old. But anyways I installed the sensor and the CEL hasn't come back since either.
 

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2000 SRP 2.5RS Coupe
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Well I replaced the knock sensor, I also replaced the battery at the same time, since apparently the on that I had in there wasn't the correct one to begin with, I bought the car used and the battery was a smaller one and had a lower rating and it was old. But anyways I installed the sensor and the CEL hasn't come back since either.
Told ya so. I had the same problem.
 

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Premium Member
98 RSTi
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165 Posts
OK bringing this back to life, hope Im not going crazy. I started to have the classic phantom P0325 code, so I Remove the wire and checked the resistance Spec is between 700 and 400 K ohms. Mine tested @ 1.50 M Ohms, way out of spec. So I order this sensor and install it. the light comes back on the next day. FML!!! now it comes and goes with out rhyme or reanson. I set up my Meter to check what happens to the voltage from the KS sensor then the Cel comes on.

Normal is about 2.4 v DC
cel comes on after a drop to .199v DC to -0.80 v DC( yes it changes polarity)

Ive come to 2 possibilities
A- I was sent a freak of nature Bad OEM Knock sensor

B- I have a strange ass gounding problem with my car.

now here is the kicker. I kept the volt meter on the circuit after the cel came on. turned off the car and turn just the ignition on the Meter was still reading the low or inverse voltage.
Does anyone have any experience with this?????
 

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Premium Member
98 RSTi
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165 Posts
So all of your that were on the edge of yours seats all day long you can relax........ If you chose A-freak of nature bad OEM knock sensor you were correct. Time to call up Subaru Genuine get me a new part!!!
 

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95 Impreza L
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178 Posts
k....bringin back an older thread...P0325. checked resistance of knock sensor, i got 562 K ohms, which is def in spec of 400 to 700 K ohms. cleaned off mounting surface good. checked continuity between knock sensor connector and grey connector mounted on passenger side of bell..read .2 ohms, which is proper continuity.

i checked terminal #3 on the ecu connector which is what alldata pro tell me to check number 3 and ground, got a low reading, 2.542 K ohms whiched seem to be below what it call for, but not sure.

i can reset the codes, clear them, take a drive get a bout 5 or 6 miles and boom on come the light again. same code, gettin frustrated here, any one help???? thanks in advance!!!
 

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2000 SRP 2.5RS Coupe
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Umm... I would try replacing it anyways? Just return the sensor if that isn't the issue.
 

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1998 impreza 2.5rs
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630 Posts
I had the same p0325 and just cleared it several times a day. Eventually I got a loud knock in the motor and could hear it get worse and worse over about a few month period. Then it got way worse one day and soon it died on me. The motor was replaced with a '99 phase-2 motor, but left the dohc heads and everything from my car, which is a 98RS. At this point I am using the new block and the knock sensor from it. Yesterday (2 days after the motor has been replaced), I got the p0325 again. Had it three times in a day.

I'm going to replace the knock sensor to see if that fixes it in case of the off chance that two motors and two sensors just happen to have the same exact problem. Also I read it could be the fuel octane, and that fuel has been sitting for like 6 months while the motor was being built, so i'll get some fresh gas too.

In the event that it doesn't fix the problem, isn't the knock sensor connected to the ECM? Could that go bad?
 

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95 Impreza L
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178 Posts
well i did end up just gettin a new sensor, and that was it, it was a freak chance i grabbed a bad one to start with...prob fixed.
 

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1998 impreza 2.5rs
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630 Posts
And mine I put premium fuel in and it went away immediately and it hasn't been back yet (only been a day so far though, I'll update if it comes back).

(edit: It came back after about three days.)

(edit again: Replaced the knock sensor with a used one from a different motor, it had a little less corrosion on it and fixed the problem. I'll update again if it ever comes back, but as of today, 6-18-10, it works great)
 

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'72 FJ-40 w/SBC
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25 Posts
BTT Great info in this thread. :banana:

My GFs 98 2.5 RS with 286,000 miles on it (rumored to have been rebuilt 70,000 ago) had the P0325 code.

Changed the knock sensor and spark plugs (they needed it) and the CEL is now out (2 days, probably 60 miles later). I haven't checked to see if the codes are still in memory yet. I need to get my own code reader. It needs to be clear for her to pass smog here in NV.



BTW, it had P0303 and P0304 codes (missfires) and P0420 (cat system) codes as well as the P0325 when she bought it. My neighbor cleared the codes, she put high octain in it and ran it for a few days before checking it again. Only the 325 code came back within that time (with the cat system still not reporting yet). The CEL was on and off during that time. As I said above, the CEL seems to be constantly off now, 2 days after replacing the knock sensor.
 

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'72 FJ-40 w/SBC
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25 Posts
Many miles later and several other problems fixed and the 325 never came back.

Still a CEL she just told me about, but not a 325 in almost a month. It passed smog at least. :D

I'll read it tomorrow. :yapyap:

BTW, P0325 = change knock sensor. :)
 
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