My wifes Impreza 2001 2.2 Check engine light just came on today. I took the car over to autozone and had the codes read it came up with code P0325. I quess this is the knock sensor. The light has gone back off. this was a very brief maybe one hour deal. Should I get this looked into and spend the money, or wait and see if the light pops back on and then get it diagnosed. The knock sensor could be failing that i gather, but could it be cheap gasoline? A loose gascap or something alone those lines. Or is the P0325 code fairly cut and dry. Any help would be appreciated since I am without a clue about the mechanics of my car.

 

Thanks...Crowheart

Hm...that should have the newer version knock sensor. Make sure it's not cracked, the mating surface between the block and sensor is clean and bolt is properly torqued, and that the connector and wiring looks good.

I don't even know where the sensor is or what it looks like. I would be willing to learn though.

Knock sensor looks like the thing in the pic below. Not completely sure about the Impreza, but on Legacies it is mounted with a single bolt (through the hole) to the engine block pretty much right below where the throttle/cruise control cables connect to the throttle body.

 

This one is cracked and the wire is frayed. You don't want yours to look like this:

usually a bad knock sensor code is just that, a bad knock sensor. Not much to test on the bench, so i would just go ahead and replace it.

 

 

nipper

Do a search on the error code and/or knock sensor.

 

There are a lot of folks having issues with that little part.

 

I moved my sensor...and I still get that error message every now and then.

This one is cracked and the wire is frayed. You don't want yours to look like this

 

Yes, lol, that is a bad one...

 

While searching the threads you'll find a couple pictures I posted of where the sensor is if you have any trouble.

 

www.rockauto.com is a good place to get them cheaper than dealer.

hehe yes that knock sensor has gotten a lot of mileage. The person who had it before me must have gotten a lot of use out of it too.

hehe yes that knock sensor has gotten a lot of mileage. The person who had it before me must have gotten a lot of use out of it too.

 

I know the fellow, I'm pretty sure it had somewhere around 218k on the sensor...

Your best bet is to just replace it, I've had a few knock sensors go bad on some of the cars I own and they'll steal hp away from you by getting false readings.

If you're willing to take the risk, you can just pull the plug on the knock sensor so to speak, and replace it with say a 470 kilo-ohm or a little higher resistor. Of course the ECU will have no way to protect the timing if it does start knocking, but there won't be any power loss from the ECU retarding the timing.

 

If you don't want to chop the wire on your existing knock sensor, if you post in 'parts wanted' you will find some very friendly and willing people who will send you their old knock sensors for a few bucks. Then you can chop the connector off and use that for the resistor.

might as well just go ahead and change it. they're super easy...just a little hidden. undo one bolt with a socket (12mm, if I recall correctly) on an extension, unclip from the harness, clip the new one in and bolt it on (that's a little harder, since it's at a bad angle). Just remember the direction it was pointing then it came out and leave the new one that way. for some reason the job pays 1 hour to do for a shop, but it takes like 5 minutes to do. maybe 10. if you've taken 15, something's wrong. the sensor is #2 on the pic. the torque value given (17.4 ft/lb) basically means "light and snug, but don't go crazy"

~Erik~

All good info, had a P0325 code in my '95 legacy, loss of power to boot from the ECM backing off the timing. Wire brushed the mating surfaces, code came back after a day. New sensor from rockauto.com for $45, installed, back to full power. The Legacy has the sensor down in a 'cavern' behind the throttle body, single 12mm bolt. Folks with nimble fingers can do this job in 5 min. Mine took longer.