My truck set a check engine light the other night. So I pluged in my HPtuners scanner and it showed to be a knock sensor low voltage code. Does anyone know whatthe problem might be or how to fix it?

 

Corroded knock sensor most likely. You'll have to replace it.

 

There's a TSB in reference to knock sensor issues...water gets under the intake and into the valley cover and corrodes the knock sensors and possibly the sub-harness to them. GM wants you to replace the knock sensors if corroded, and I *think* possibly the sub-harness if the terminals in the connector are all green. After the new parts are installed, you have to build a "dam" with RTV around the knock sensors to stop water from getting into them. I've seen pics around here somewhere, where somebody has done the repair with the RTV...may be in the GM section.

 

im in the process of doin it right now. its pretty easy, just time consuming

 

Im getting code "P0327 Knock Sensor Low Voltage"... I have access to another knock sensor, how do I go about changing it?

 

Pull the intake off and they are right there on the valley cover. There are rubber gromets were the wires go down to the knock sensors, just rtv around those before you put them back in and that will seal them better then the rtv damn the tsb recommends (just makes them alittle harder to get back out). Then pull the back foam piece off the intake so any water that gets in there can run out down the back of the motor (also recommended by the tsb). Not to bad of a job, take a few hours if you're not rushing. I would also recommend replaceing the intake gaskets while you are in there.

 

Well pictures are worth a thousand words so here are some random pics I have of Knock Sensor replacement and sealing. Enjoy!

Picture of Knock Sensors deep in the valley cover:



You have to squeeze the clip on the opposite "wide" end of the clip to release it from the knock sensor stem:



Another look from the side:



Once you swap the sensors use some RTV to keep the moisture out. I personally did not get too crazy with it, just made sure it sealed the boot:



Here is another picture of someone on this site and how they approached the "Dam O' Silicone" to keep the water out:

 

That should do it!