Thread: P0332

did you drain out or use up all the gas from the new gas station? did it knock at all?

my first step would be to remove the gas from the new gas station (put in gas can in case its not bad) then run a tank of premium. if the light comes back on then you will know for use its not bad fuel or low octane. from there then you would be able to look into testing the knock sensor and go from there (i'm not sure how to do that stuff lol)

Your rear knock sensor is acting up. It likely has gotten wet (typical on some LS based engines). You could start by checking the jumper harness at the back of the intake manifold for signs of damage. It'll be the wires that come out from under the intake manifold down in the back of the engine. There should be an electrical connection there.

To replace the knock sensor, you have to pull the intake manifold off. It isn't that difficult of a procedure, but can be time consuming the first time.

Your rear knock sensor prob got loaded with moisture and water and corroded /shorted out. Happens to nearly all 99 up GM truck that ever had the engine get wet, through washing, mudding, etc.

Edit, Swartlkk beat me to it!

Originally Posted by swartlkk

Your rear knock sensor is acting up. It likely has gotten wet (typical on some LS based engines). You could start by checking the jumper harness at the back of the intake manifold for signs of damage. It'll be the wires that come out from under the intake manifold down in the back of the engine. There should be an electrical connection there.

To replace the knock sensor, you have to pull the intake manifold off. It isn't that difficult of a procedure, but can be time consuming the first time.

Its been raining pretty heavy lately and I've had to traverse some really flooded roads so that makes sense that it might have gotten wet.

Ill have to check that connection out tomorrow when i get off work since its a bit dark out at the moment. As for the replacement procedure, i assume its just unbolt manifold, change sensor, lay down sealant and bolt it back?

No sealer on the intake manifold gaskets. They are reusable. Use some RTV around the knock sensor to seal it to the lifter valley cover (might as well clean and seal up the front one too).

Originally Posted by swartlkk

No sealer on the intake manifold gaskets. They are reusable. Use some RTV around the knock sensor to seal it to the lifter valley cover (might as well clean and seal up the front one too).

Ok cool, didnt know they were re-usable. Definitely will hit the sensors with the RTV, dont want to take this apart more than once, LOL.

Thanks for the tips Kyle, you are the man as always.

Well, i got out of work early today so i just went down to checker and picked up a knock sensor. Ill try and see if i can get it swapped out. Taking a look at the top of the engine though, it seems that intake manifold has quite a bit of stuff connected to it so this might take a while like ya said. Just to be on the safe side im going to pick up a chiltons manual to help me through it in case i get stuck.

As for the topside connector to the sensor, i think i found it but im not sure. I took a picture to be sure. Is this by chance it? If so it looks just fine, no damage at all to it.




Edit: Well just got the manual and um damn there is a bit to do. I think i can do it in one day but i think im gonna get a buddy to give me a hand just in case. However the illustrations make the knock sensor much easier to identify and locate. When you said it was under the intake manifold, you werent kidding, lol.

The job ain't that bad at all, I've already done it about 3 times, lol. It took me about 2 1/2 hrs last time, but I'm also the kinda guy that's real meticulous, making sure everything is spotless. Don't forget to use di-electric grease on the connections to add just a little extra protection against moisture.

Originally Posted by Beatdown Z

The job ain't that bad at all, I've already done it about 3 times, lol. It took me about 2 1/2 hrs last time, but I'm also the kinda guy that's real meticulous, making sure everything is spotless. Don't forget to use di-electric grease on the connections to add just a little extra protection against moisture.

One step ahead of ya on the dielectric grease. And as for time, i litterally just finished. Took me 8 1/2 hours start to finish and i did it all on my own. Had a few hiccups like loosing an o-ring on the fuel rail and having a SOB time trying to get the injectors back in. At any rate its fixed and the code is off. Ill have to take it on the freeway to see if it comes back but already its running much better. As for the old knock sensor, holy hell was that thing boned. Ill post up a pick of it after i take a shower. Its completely rusted over and it was sitting in about a half inch of rain water. The front one was dry as a bone thankfully but i sealed both of the plugs up just to be sure.


EDIT: Pics uploaded

This is the area under the intake where the sensors were, notice all the grime where the back sensor is.



Sensor comparison......yeah that old one was toasted.

Here's what mine looked like. Took the truck muddin' maybe 6 times. LOL

Wow, um damn. Guess mine was almost clean in comparison, LOL.

I think half the problem with that area is that the foam blocks on either end of manifold cavity arent worth a crap. I was half temped to cut out some sheets of ABS plastic and RTV'ing them in place of the foam.....but by that point i was tired of looking at the damn engine, LOL.


Oh, one interesting point i found out on my engine, it doesnt have an EGR valve. When going through the chilton manual it showed where its supposed to be and when i went to look at mine, low and behold its not there and the spot where its supposed to be is solid plastic. So I'm like, score, one less headache to worry about.


Edit: Just went out to the silverado and I smelled gas.....turns out the back 2 injectors on the drivers side have a small leak. I had a feeling they might leak at some point as when i pulled them out yesterday the rubber seal where it meets the fuel rail on those 2 were missing a small chunk on each.....so now i gotta get seals for those. Thankfully it doesn't seem to be leaking really bad, as its just barely coating the injector in gas and the area around them is bone dry. At least now i know how to change them easier so when i get my next check i can pull them out and get them fixed quickly.

Started the truck last night and the code is back......GRRRRRR

I think there may be still some grime and moisture under the sensor though i tried my best to clean it all out. I'm going to give it another try tomorrow unless someone has any other idea why the code came right back.

Did you replace the harness? Also, did you torque the knock sensor to the right torque spec?

Originally Posted by Beatdown Z

Did you replace the harness? Also, did you torque the knock sensor to the right torque spec?

The harness i did not replace. As for the sensor i couldnt find the torque specs anywhere in the haynes manual so i tightened it to snug but didnt wrench on it.


And oddly enough on the service engine light, its now coming on sometimes and then going off again. This morning it was off then came on for the next couple starts and now its off again. Im betting that its likely just the harness since when i pulled the rubber plugs out it stripped some of the sheilding off the wires but not enough to expose any of the wire itself (kinda skimmed about half the thickness of the plastic off. Ill change the harness next weekend and see if that helps.

Knock sensor torque is 15 ft-lb (Texas F-Body 4th Generation Torque Specifications). Also, what brand sensors did you use?

I cant imagine that I imparted any more than 15 ft lbs when i put it in but i will check it to be sure. As for the knock sensor, the manufacturer is BWD.