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Discussion Starter · #1 ·
Bad knock sensor, full of water. Replaced both and the wiring with GM parts. I didn't catch the part about 15 foot pounds. I proceeded to pull it back apart, used new GM sensors in cause I had over torqued the first ones. Now I still have the codes for low signal for both. I have checked the wires to the ECU , no problem found. I am almost convinced the ECM is bad although the truck runs fine. Any one have any ideas because I am fresh out.
 

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2000 Silverado Z71 4x4 5.3L 480k+ miles w/ GM rebuilt motor and trans
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Was the area around them and the holes in which the sensors live corroded? How well did you clean down there? It may be they are not grounded very well from corrosion, which would SUCK to have to take apart for a third time...
 

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Discussion Starter · #3 ·
Not a corrosion I'm pretty sure. I cleaned everything well. Yes it would suck to take it apart but I'm getting pretty good at it. I keep coming back to the ECM being bad. Apparently it also controls the low coolant light and that also quit working about the same time. I would hate to spend $200 and be wrong.
 

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Just confirming you replaced the knock sensor wiring harness too? I had an 02 5.3 Suburban where the knock sensors failed. I used to clean my engine with a pressure washer regularly and was unaware that the knock sensor were below the intake manifold. After I replaced them the fix was good for about 4 years and 70K later. Then knock sensor codes appeared again. Replaced them. Code came back. Replaced them again. Codes came back. Replaced ECU. Codes came back. Could never figure it out. Sold the truck with 200K miles on it.
 
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