5.3l engine knock
 

My truck has been popping Bank 2 Knock Sensor codes for the last week or so. I get them reset and it comes back the next day. Was going to just replace the sensors, but wanted to upload a video and see if I actually have any engine knock. I hear some noise, but I'm thinking it could just be valvetrain and not true knock. Please take a listen on this video and tell me what you think.

Re: 5.3l engine knock
 

I can't hear anything bad(But I have been told I need a hearing aid)...Those sensors do go out more than others due to their location and water getting to them.

Re: 5.3l engine knock
 

Ok, I swapped both of the knock sensors and drove it for about 5-600 miles. Then the codes have started popping again. I had recently replaced the spark plugs with NGK's, so I pulled them and put factories back in. Codes have reappeared after that swap. There doesn't appear to be any real knock, and the codes don't pop immediately they take at least 70-100 miles of driving before they come back. Can anyone suggest anything else to look at?

Re: 5.3l engine knock
 

Whats the code number?

Re: 5.3l engine knock
 

0332 low input voltage bank 2
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Re: 5.3l engine knock
 

Also, thought I'd toss this out there. My truck is running cutoff exhaust after the cats. When I let off the gas quickly (like passing someone) I get several pops from ( I assume) air being pulled back through the exhaust. The codes don't seem to pop when I'm getting that noise, but I thought it might be relevant

Also, mu bank 2 sensor was just nasty with mud and rust. I took 3 blue shop towels and cleaned it out the best I could. Couldn't vacuum sine I did it with the intake on.
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Re: 5.3l engine knock
 

The "cut off exhaust" is causing your problem. Put a exhaust system on it!

Re: 5.3l engine knock
 

It was like that when I got it, sadly. You think that's it? I drove it for a month or so after I got it, but I could see how the engine would see that as knock if it makes it all the way back to the block.
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Re: 5.3l engine knock
 

You need a exhaust system anyway. I never thought of it as "optional";)

Re: 5.3l engine knock
 

It isn't as loud as you'd imagine. If it isnt causing these sensors to pop errors I really don't think I'd put one on
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Re: 5.3l engine knock
 

In your video it sounds like a tractor.

Re: 5.3l engine knock
 

That's all under hood noise. You can't hear the exhaust note in the vid cause it's pretty quiet. The cats seem to do a fair job of killing the sound. I'm really only concerned with the knock sensor issue, not how the truck sounds
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Re: 5.3l engine knock
 

disconnect the 2 pin connector on the top of the intake for the knock sensors [blue wires] ohm each wire to ground should have 93k to 107k ohms if not in spec remove the intake and check the wiring to the sensors or possibly water down in the holes where the sensors are. gm technical service bulletin 02-06-04-023a

Re: 5.3l engine knock
 

EDIT, What hay hauler said

Re: 5.3l engine knock
 

I was planning on trying to do this tomorrow, but I didn't know where to check the wires at. I am afraid that the wiring harness is bad, is there a way to differentiate between bad harness and bad sensor?
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Re: 5.3l engine knock
 

The full code is p0332 knock sensor 2 circuit low input (bank2)

Sorry, probably bad abbreviation on my part
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Re: 5.3l engine knock
 

Also thanks for the help all. I got my hands full on my project truck, don't wanna be wasting time wrenching on my daily!
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Re: 5.3l engine knock
 

if the ohm test fails the intake has to come off any way. then you can test the harness and the sensors

Re: 5.3l engine knock
 

Could be harmless piston slap as well............at least concerning noise.

Re: 5.3l engine knock
 

not to hijack this thread, but are 5.3s prone to piston slap? i think my tahoe has a case of it, goes away after either a couple minutes of warm-up idle or about a 1/16th of a mile. and the motor has to be dead cold for it to happen

Re: 5.3l engine knock
 

5.3s and 6.0s are pretty prone to cold start knock. They just knock for the first min or two in the morning. In 03 they started putting a coating on the piston side skirts to help.

Re: 5.3l engine knock
 

Well, I disconnected the battery and let it set for a bit.... that clears the ECM completely I suppose because it also idled a bit funny for a second trying to figure itself out after I restarted it. That cleared the light of course, and I drove it for a couple weeks before the light came back on. But this time it stayed on for only about 30 min and then went back off.... so far hasn't come back after that. Keeping my fingers crossed.

Re: 5.3l engine knock
 

You most likely need both knock sensors and probably a knock sensor harness. If it is setting a code there is a problem that isn't going to just "go away". Those trucks tend to get water in the knock sensor bores and it causes corrosion on/in the sensors and connectors. I have done more of them than I can even count for the exact code and every single one of them was due to water in the knock sensor hole....

Re: 5.3l engine knock
 

Yeah, I know about the water problems so I already replaced the sensors.