My girls 2005 silverado 5.3 thru a rear knock sensor code, i thought maybe its because she put 87 on this fill up, normaly she puts 91 every time, so i put 91 in it, cleared the codes and drive it for a few miles and the same code poped up on the third ignition cycle. i just picked up two new knock sensors, the wire harness, and intake gaskets from the local chevy dealer $200 later, i planed on installing the new knock sensors/wire harness this week end but thought i should askes some of your opinions on if im on the right track with this? also how hard is this job? thanks David!

 

I think that you'll have it covered with all that, it's common for the knock sensors to corrode from water intrusion, there's a TSB in reference to this...if you search the GM section for "knock sensor", you should find pics that guys have posted of their knock sensors with a dam of RTV around where they go through the valley cover, as outlined in the TSB.

 

Thanks, i will have to look thru some of the TSB on All Data at work. i just remembered that i power washed the eninge off around three months ago maybe thats why the rear knock sensor thru a code.

 

That seems very plausible. Knock itself shouldn't cause a SES light generally,.

 

Thanks that was also something i was wondering. so bottom line the its got to be the rear sensor. any tips on this job? looks like it only pays around 2.5 hours so cant be that hard

 

Not too hard, but use a ring of black RTV around the plastic cover to keep out any moisture, and don't over tighten the sensors. The blower is a b*tch to pull off though, as you probably know, so good call to replace both while you're in there.

 

Torque is critical on these sensors. 15 lb ft.

 

This is true, if they're over-torqued they will be over-sensitive

 

thanks alot!

 

I never got a code for bad rear knock. If you log the truck at wot it should be pulling 8* timing to protect it's self. It really easy to change these.