GMT 800 & Older GM General Discussion 2006 & Older Trucks | General Discussion

Knock Sensor 2 Low circuit input

Old Jun 15, 2010 | 10:08 AM
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Default Knock Sensor 2 Low circuit input

I read a lot of threads about replaceing the knock sensor. I just wanted to make sure that is what the code means!

The reason is because my plug wires sucked, and at night looked like a light party off my headers under the hood! I HAD NO SES LIGHT AT THIS TIME>

I changed them to tyler 409s and got the boot protectors. I didnt change the plugs because when i installed the headers about 5000 miles ago i put the tr 55 ngk in, with a tune.

So my question is simple did i bump anything to cause this code or is it just luck to the draw they went out at same time i chose to install plug wires.

I did not pressure wash the engine bay.
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Old Jun 16, 2010 | 08:46 PM
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Yep time to change the knock sensors. You will want to change the harness as well will you are in there as they have problems with that as well and it is not that much more.
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Old Jun 16, 2010 | 11:23 PM
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Be sure to tighten the new knock sensors to 14 ft lbs.
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Old Jun 17, 2010 | 12:40 AM
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Just did both knock sensors and harness on my truck a few weeks ago. I had the same code as you. It was not to bad of a job, took 2 hours with oil change and it was my first time. there was alot of dirt, leafs, and crude under the intake manifold that i made sure and vacuumed up. Also make sure and torque the new knock sensors as -Mrgoodwrench- stated above other wise you might run into fails knock problems due to it being a sensitive piezoelectric sensor. Good luck!
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Old Jun 28, 2010 | 12:10 PM
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I did mine not too long ago, Half of texas was under my intake Manifold. Make sure to buy some high temp silicone while your getting parts at the store. You will want to make a small moon shape bead around the knock sensors with the opening to the moon facing the rear of the truck, this will keep water from leaking into the boot of the sensor and causing it to fail. Make sure to remove the foam blocks on your intake mani and throw em away!

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Old Jun 28, 2010 | 10:52 PM
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GM's little dam idea seems kind of cheesy to me. I always clean the grommets up good with brake cleaner along with the holes the knock sensors go in and then apply a fairly thick bead all the way around the grommet. Pop the grommet into the hole and the excess silicone pushes out and forms a ridge all the way around the grommet. Then I shoot some silicone in around the wire where it passes through the grommet as well as a small mound around the wire itself. I've never put the little dam up and never had an issue with my method. You can still get the grommets back out but it takes a little prying. I found this out when the parts guy dropped one of the knock sensors without telling me about it and the next day it stopped working and I got to do the job over again.
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Old Jun 29, 2010 | 01:14 PM
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Originally Posted by oldred95
GM's little dam idea seems kind of cheesy to me. I always clean the grommets up good with brake cleaner along with the holes the knock sensors go in and then apply a fairly thick bead all the way around the grommet. Pop the grommet into the hole and the excess silicone pushes out and forms a ridge all the way around the grommet. Then I shoot some silicone in around the wire where it passes through the grommet as well as a small mound around the wire itself. I've never put the little dam up and never had an issue with my method. You can still get the grommets back out but it takes a little prying. I found this out when the parts guy dropped one of the knock sensors without telling me about it and the next day it stopped working and I got to do the job over again.
That will work too. Did you remove the foam blocks from the intake? I know GM installed 'em there to keep water and mud out but from what I have seen It just keeps it in.
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Old Jun 29, 2010 | 06:31 PM
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Originally Posted by Killtank
That will work too. Did you remove the foam blocks from the intake? I know GM installed 'em there to keep water and mud out but from what I have seen It just keeps it in.
Sure did. It also traps heat in there which leads to intake warpage.
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