Knock Sensor CEL causes?

[06Z71guy]

I have had my 2006 (176k) since Jan of this year. Shortly after, around 250 miles of driving. the CEL with Knock Sensor codes for both knock sensors came on. I found a HEAVILY corroded bank 2 sensor when I took off the manifold. I replaced BOTH knock sensors with OEM/Delco sensors, and an aftermarket (Dornan) harness. Since then, I still get the codes after driving anywhere from 50 miles, to about 200 miles. Mostly for bank 2, but occasionally for both. I clear the codes with the scanner, and they eventualy come back. I dont THINK I see or feel any particular knock, sound or performance issues with the CEL on, but its friggin annoying as hell. I'm not opposed to going back in, and perhaps using an OEM harness, as I feel, potentially, the aftermarket harness may be the issue., However...is there any (external from the knock sensors and harness) parts I can also replace, in an effort to stop the annoynace? I use premium fuel, and dont drive the truck hard, at all. No vaccumm leaks that I am aware of, no rough idle. When I removed the manifold I also cleaned the intakes on both sides. They were cruddy, but were nearly spotless when I was done. Could it be plugs, or timing? Again, no detectable performance issues...

Any practical advice, especially if its first hand expeience, is greatly appreciated!

 

[2004Slickside]

Same exact situation with my 2004 Z71. Used Delco parts. Betting it is some sort of further corrosion in the wiring to the PCM but haven't had the motivation yet to track it down.

 

[EXT4ME]

Looks like you have already addressed the primary culprits.

Installing an OEM harness is never a bad thing, however.

Since you have already covered most of the usual suspects, I wanted to pass along something I came across a while back.

On a couple of posts I have seen out on other sites, there were owners that were also chasing weird CEL's dealing with misfires and such.

After extensive troubleshooting, the root cause was finally stumbled upon.

The main serpentine accessory belt and/or pulleys and idlers.

It appeared that some sort of imbalance in the belt drivetrain was causing a resonant frequency at certain engine RPMs that was being picked up by the knock sensors and therefore causing the computer to throw a CEL.

While I have never experienced this phenomenon personally, the theory seems plausible enough for me to try to remember it for future reference.

Just keep this in your back pocket in case nothing else seems to work.

Best of luck with your repair.

 

[06Z71guy]

I

Same exact situation with my 2004 Z71. Used Delco parts. Betting it is some sort of further corrosion in the wiring to the PCM but haven't had the motivation yet to track it down.

I'll eventually dig back in there. When a replaced the sensors, I also did the recommended actions: Removed the REAR foam blocker that holds water under the manifold. I sealed the circular discs that house the knock sensors and built an RTV dam around the front of the engine, under the manifold to divert any water to the sides and out the rear, made possible with the removale of the foam blocker. It is what it is. I still love my Avy...would loe it that much more if I could clear up this nusiance.