Warning!!! Do not wash your engines with water or it will cost you over $200 in parts and 3 hours labor to repair. I recently did a shiat load of maintenance on my 06 Silverado. I changed all the fluids, Wheel bearings, Shocks, O2 Sensor, and brakes. Pulled out the pressure washer and decided to give the engine compartment a bath....WRONG!!! Under the intake of the engines there is a flat pan the bolts to the valley of the engine in between the heads. In the middle of this pan is your engine Knock sensors. Two of them!!! They are counter sunk below the pan and have a rubber grommet that seals around the access hole in the pan and the wire then go through the grommet and plug into the Knock Sensor. Well the water from washing you engine gathers on the pan on seeps past the rubber grommets and then fills the cavity around the sensor causing it to short out and throw a code.You check engine light will come on and when you check it with a scanner it will be a code P0332 low voltage knock sensor. your truck will not have much power and mileage drops about 3 Mpg...Leave them dirty!!!! You can search the web and find this is very common problem with GM engines. The fix is to replace the 2 sensors,wiring harness and intake gaskets...Using a bead of silicone on the new rubber grommets building a dam to keep the water from leaking into the cavity around the sensor. One more time....LEAVE THE ENGINE DIRTY!!!!

thanks for the info i washed my 08 once and decided not to do it again and now i wont. just have to wipe it down

I bought a new one last year. I just broke 15k miles and while getting my oil changed they discovered a small oil leak coming from behind the engine. I thought it was the rear main seal but it was said to be small voids where a rear cover attaches to the engine. Under warranty so no cost to me, but still bs.

I haven't washed either of my trucks but maybe once or twice. Guess I don't have to worry about this problem. Just transmissions. Lol


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coastal, I had to change these sensors out before on mine also. I have the 6.0, you might wanna ask them if they put rtv around the sensors. ifthey did, you wont ahve this problem again.

Going to change them out in the morning. I refuse to pay $300 for labor. Got me a new tube of black RTV.

I called everyone in town and the cheapest was $300 plus parts. Dealership quote was $640.

Thats just what Obama wants you to believe......








IN all realness and I wasnt gonna read the whole thing, but why did you wash your motor again??

What is this wash thing you speak of?

its common for the knock sensors to go out...


i know that the 96-99 5.7 can take a lot of abuse and water up to the headlights!

Go to the automparts store and get you some fuel line disconnecters after that it's cake bgoing back together use lotion or oil to put your injectors back in if not tear o ring. Been there done it

Good job, Dick! Wash your motor while its running. The hot engine will dry the water before it gets into those places.

Took me 1 1/2 hours to do the job. The rubber grommets were not sealing at all. Wish I would have taken pictures of the sensors.They looked like they were in saltwater for a few weeks.

Seen this happen alot. The RTV will do the trick. COpe did you have alot of leaves under the intake manifold? What it dose is retard the timing so you dont get optimum spark advance at various throttle positions. You can clean them, But a rag and some degreaser works well too. Once you RTV it..... you can wash all you want!

Yes. I'm glad you mentioned that. The foam cause moisture to stay under the intake and i think causes more harm than good!

I always washed mine while it was running and never had a problem (4.8l) GMC, but thanks for the heads up, i now drive a diesel and no problems yet while washing the engine bay. Good find sucks you had to spend money to tell us about it!

Just so everyone knows, on the new body style trucks the knock sensors are on the sides of the block and not in the valley.

cope imma get with u one day this week and call ya.. thats the code coming up on my truck. and hell yea im notiicn the fuel drop bad!!

haha, raced a cammed 6L rcsb the other night. definitely some motivation for me to go ahead and buy heads and injectors so i can put mine in and go fast too

Im ready to see what the 6.0L will do in your truck!

[quote="Dalton"]damn 200 for parts and 3 hours labor knock sensors are $50 a piece, rtv $7 for a tube and the knock sensor harness which can also go bad when replacing them is around $30.


Don't have receipts in hand.

2- AC Delco Sensors $92 Parts House
1- Harness (Dealer Item Only) $57
1- FEL-PRO Intake Manifold Gasket Set $56 Parts House
1- Black RTV $7.64
Total $212.64

I don't use Vato Zone part and replace them every 3 months!!!!

i go tmine from oreilly's, before i started working there. i wouldnt go to autozone either

The dealer in my town told me that if the NBS trucks are parked at the "just right" decline angle that a hard rain can go down the windshield and get to the sensors. It seems crazy but I guess its possible.