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2000 Outback knock sensor, new car and yes I'm being needy


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I've got the P0325 knock sensor code. I separated the connector and read 3.2 volts from the open connector. I put the connector to the knock sensor back together and put a pin into the connector and read 2 volts. Is this the correct voltage readings? I am using a digital volt meter. I pulled the knock sensor and it doesn't appear to have any cracks in the casing. I cleaned the metal surface on the sensor and the block where it attaches. Put it back and cleared the code. Did a couple miles driving and the code reappeared. More tests or replace?

 

Also, the heat shields are rattling at certain rpm's an I need to secure them better. Could they be triggering the knock sensor for some reason?

Edited by maestro
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When you mix vibration and wiring all things seem to become possible but I do not believe the two are related.  I don't know if this is relevant in this case but sometimes when we get a code like that, even though the work has been done, the code still needs to be "cleared".  At this point this could be your issue (13 year old car the computers were less advanced).

 

If not it seems to me that you have done your due diligence I would replace it...there may be a mechanic who posts that has another thing for you to check.

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I've got the P0325 knock sensor code. I separated the connector and read 3.2 volts from the open connector. I put the connector to the knock sensor back together and put a pin into the connector and read 2 volts. Is this the correct voltage readings? I am using a digital volt meter. I pulled the knock sensor and it doesn't appear to have any cracks in the casing. I cleaned the metal surface on the sensor and the block where it attaches. Put it back and cleared the code. Did a couple miles driving and the code reappeared. More tests or replace?

 

Also, the heat shields are rattling at certain rpm's an I need to secure them better. Could they be triggering the knock sensor for some reason?

No, rattling heat shields don't trigger the knock sensor. Suggest just keep on driving, if the CEL for knock sensor stays off. Did you clear the code, or remove, and re-install the battery cable after a 5-10 minute wait? Sometimes, no code clearing is necessary, if the knock sensor is working properly. Also, I seem to remember that new knock sensors are available on the cheap on e-bay or Amazon.

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Voltage isn't the issue at the knock sensor, its the resistance of the sensor element, and the signals that get sent back to the ECU, which can really only be recorded with an O-scope. If you get a code and the wiring isn't chewed up, replace the sensor.

 

Heat shields are easy, get a couple 2-1/4" pipe clamps from the auto parts store and bolt them onto the pipes over top of the heat shields. You may have to remove the bolts on the ends and bend the little "wings" in, but they're a permanent fix for heat shield rattles.

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Or you can pop in a 560k ohm resistor to keep her happy, but the ecu will not then be able to retard timing if it does detect spark (but if everything is sound mechanically usually running premium fuel will let you run like this).

 

Right that code _never_ means it is actually detecting knock (there is no indication to the user when it detects knock; it just retards the timing).

Edited by porcupine73
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  • 2 weeks later...

I'm also getting this code on rare occasions.  I've cleared it but it does recurr.  Hasn't doen it for a few weeks now and it seems to drive the same even when the check engine light comes on.  No other codes appear.

 

This is on a 95 Outback L wagon and they say you have to tear the whole top assembly, intake manifold etc. off to get to it.  Just as soon not do that.

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I'm also getting this code on rare occasions.  I've cleared it but it does recurr.  Hasn't doen it for a few weeks now and it seems to drive the same even when the check engine light comes on.  No other codes appear.

 

This is on a 95 Outback L wagon and they say you have to tear the whole top assembly, intake manifold etc. off to get to it.  Just as soon not do that.

replace the knock sensor.  it doesn't require removing all that stuff - takes 15 minutes.  yours is even easier than some. 

$15, 15 minutes, done.

 

this issue is so common you're best off just replacing it with new now and being done with it.

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I changed my knock sensor a week ago and have not seen that code since. Like the others say, it is a breeze to change. Just use long extensions and be sure to take note of the orientation of the knock sensor before you remove the old one. Put the new one back in the same way or you risk cracking the new one. However I am still getting the P0420 catalyst error code.

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