stlnet Posted May 17, 2009 Share Posted May 17, 2009 Problem: The Check Engine Light appeared, and the car lost power while driving. After a few minutes, the light went off and the car felt normal again. Diagnostic confirmed knock sensor error. Solution: Replace the knock sensor. Tools required: 1/2" Wrench 1/2" Torque wrench 13 mm pipe and angled connector 10 mm spanner Estimated time: 10 minutes The knock sensor is located under the left rear intake manifold runner (for cylinder No. 4), on top of the engine block, to the left of the engine. The knock sensor monitors engine vibration caused by detonation. Basically, a knock sensor converts engine vibration to an electrial signal. When the knock sensor detects a knock in one of the cylinders, it signals the PCM so that the PCM can retard ignition timing accordingly. The knock sensor contains a piezoelectric material, a certain type of piezoresistive crystal, that has the ability to produce a voltage when subjected to a mechanical stress. The PCM doesn't respond to the knock sensor's input when the engine is idling; it only respons when the engine reaches a spesific speed. http://www.subarudrivers.net/media/knock1.jpg Disconnect the negative battery cable. http://www.subarudrivers.net/media/knock3.jpg http://www.subarudrivers.net/media/knock2.jpg Locate the knock sensor retaining bolt. http://www.subarudrivers.net/media/knock4.jpg Disconnect the knock sensor plug. http://www.subarudrivers.net/media/knock5.jpg http://www.subarudrivers.net/media/knock6.jpg Make a visible mark, so that you can install the new knock sensor in the same angle. http://www.subarudrivers.net/media/knock7.jpg http://www.subarudrivers.net/media/knock8.jpg Insert the pipe and remove the knock sensor retaining bolt, and the knock sensor. http://www.subarudrivers.net/media/knock10.jpg http://www.subarudrivers.net/media/knock9.jpg http://www.subarudrivers.net/media/knock11.jpg Install the new knock sensor, using the same position (the pigtail harness should be at approximately a 60-degree angle to the back of the engine, but using the mark you made is fine) as the old sensor. Tighten the knock sensor retaining bolt to the correct torque, 209 in-lbs (23.6 Nm). Connect the battery and your done. Link to comment Share on other sites More sharing options...
elshankos Posted October 27, 2009 Share Posted October 27, 2009 Hi there, This is a really great post - thanks! Im new to the forum and Ive just purchased a 1998 GT-B (3rd generation because its japanese) here in japan and I now have a CEL. Its the knock sensor error. My question is: you say that a knock sensor only registers at a certain speed? My CEL comes on when the car is idling. BUT - its really intermittent - sometimes it comes on when I start the car and sticks around for a few minutes before going away. Sometimes it comes on for a little while once Ive been driving for a while. Sometimes it doesn't come on at all! The car does seem to vibrate a TINY bit more than one might expect when idling but otherwise its great. Any ideas about the intermittent CEL - sensor failure? Many thanks again. Link to comment Share on other sites More sharing options...
peeksnit Posted January 30, 2010 Share Posted January 30, 2010 Great post and really helped. Problem was I had to replace 3 times and maybe came close to 10 minutes once. Reason for replacements was that I did not us OEM Knock Sensor and kept getting error. Called a GREAT service dept mgr who said have to use OEM. End of Problem!!! Last time with OEM took longer than first fyi.....i think the lead wire was thicker or something and had more trouble getting into place. Tdi Link to comment Share on other sites More sharing options...
Mickeytl Posted January 30, 2010 Share Posted January 30, 2010 Wow, that's all it took. The dealer quoted me $180 just to replace the knock sensor. But I didn't do it. Link to comment Share on other sites More sharing options...
JimmEh Posted May 9, 2010 Share Posted May 9, 2010 i'm getting p0325 "knock sensor circuit malfunction" replacing the sensor soon. Link to comment Share on other sites More sharing options...
colt45 Posted July 8, 2010 Share Posted July 8, 2010 ok got the replacement sensor tooh the stock TMIC off ;found the sensor cannot get a standard rachet in to access the bolt its angled and the rest of the intercooler blocks it can't believe that has to be taken off too since i am now in stupidville can someone recommend the tool to access the knock sensor bolt will an offset closed end wrench work? a pipe angle rachet? thanks Link to comment Share on other sites More sharing options...
dschultz Posted July 8, 2010 Share Posted July 8, 2010 Use a crowfoot flare wrench on the end of a long ratchet extension. i.e.: http://buy1.snapon.com/catalog/item.asp?item_ID=2176&group_ID=266 Not sure if the bolt is 10 or 12mm. Link to comment Share on other sites More sharing options...
colt45 Posted July 8, 2010 Share Posted July 8, 2010 thanks!! Link to comment Share on other sites More sharing options...
colt45 Posted July 9, 2010 Share Posted July 9, 2010 fwiw got mine on last night check engine light off everything A OK post mortum sears sells a split swivel socket which worked great size is 12mm also the socket magnet sold separately worked great for when you have to get the sensor and bolt threaded in that dreaded tight space Link to comment Share on other sites More sharing options...
GreenLeggy Posted January 7, 2011 Share Posted January 7, 2011 Does anyone else not have access to the photos? All I see is little squares with a ? in them. Anyone have access to these photos? I just got the dreaded P0325 and am thinking of just replacing my sensor... Link to comment Share on other sites More sharing options...
GreenLeggy Posted January 8, 2011 Share Posted January 8, 2011 N/M - I found the whole process on video. Thanks anyway Link to comment Share on other sites More sharing options...
gthaley7 Posted January 21, 2011 Share Posted January 21, 2011 I replaced my Knock Sensor on a 1997 lagacy L. Now when I start the car it runs for 5 seconds then dies? Any thoughts? Link to comment Share on other sites More sharing options...
GreenLeggy Posted February 17, 2011 Share Posted February 17, 2011 Did you check all the connections? If you unplugged any connectors, make sure you re-connect them again. When I replaced mine recently, I unplugged a total of three things: Negative battery terminal Plug to the Throttle-body (to make it easier to get to the sensor with the extension) I almost forgot to plug this one back in. Plug to the sensor Did you tighten the sensor properly? (enough, not too much) Are you getting any codes? Re-check all your connections Link to comment Share on other sites More sharing options...
zerohennie1 Posted February 16, 2012 Share Posted February 16, 2012 hi all, does anyone have a link to the video or pics? I am getting my new KS tonight and would like to install it Thanks Link to comment Share on other sites More sharing options...
Brunex Posted August 21, 2012 Share Posted August 21, 2012 yea what happened to the pictures? I just got the CEL with the knock sensor code. Link to comment Share on other sites More sharing options...
SBT Posted August 22, 2012 Share Posted August 22, 2012 Op, thanks for posting this up. Would be great if the pictures were loaded to the site for longevity's sake. PM if you have questions about how to do that. - Pro amore Dei et patriam et populum - Link to comment Share on other sites More sharing options...
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