Knock Sensor replacement Chevy 2003 5.3 litre

The wonderful county government (under pressure from EPA) is going to revoke my registration if I don’t get emissions test done this week.

Can’t pass emissions test because check engine light is on and has P0332 code (Knock Sensor 2 Circuit Low Input (Bank 2)).


Quote from mechanic was pushing $900 since have to pull the intake manifold in order to access the engine block to where the knock sensors are installed.  Parts (including new wiring harness) are $200, so I am going to try to do it myself.

It is a beautiful Saturday, I should be out doing something fun, but no, here I am getting dirty and frustrated.

Here is how it looks before starting:



Here is cover, air intake, throttle body and alternator removed. Probably really didn’t need to remove alternator, but I wanted extra room to slide the intake manifold out from under the wiring harnesses.



Quite a few electrical connectors and vacuum hoses, but finally the intake manifold is removed. I read some posts and watched some youtube videos, some guys remove the fuel rails and injectors, some guys disconnected the fuel lines and remove the entire intake as an assembly. I do not have the fuel line connector release tool, and I did not want to remove each injector and worry about messing up the o-rings, so I decided to disconnected the hard fuel lines where they connected to the fuel rails. Simple, one screw holding flat retainer in place, and hard plastic lines pop right out (sealed by o-rings). Disconnected electrical connectors on all the injectors, and a few other electrical connectors so I had wiggle room, removed 10 nuts holding the manifold in place and it came out fairly easily.




Now to get the actual knock sensors out. They are on top of the engine block all covered in gunk. Remove the rubber covers, break off the connectors (because I have new wire harness and plastic is brittle from heat), and use 7/8 socket to remove the sensors.


Here are bad sensors. Notice one is much more corroded than the other.


Now for the cleaning. This took quite a while as I wanted to make sure the surface was clean and that nothing fell into the intake ports. Brake cleaner, paper towels, rags, elbow grease and shop vac. I made sure everything was clean and nothing had fallen in cathedrals.



Installed new knock sensors, and sealed covers with orange high temp RTV. Hopefully this will keep out the moisture and they will not go bad again. Of course, the truck has 236,000 miles, so if it runs another 200K, I guess I will change them again!


Cleaned the intake manifold and injectors and installed new manifold gasket:



Installed manifold. Since it is plastic composite, very important to follow torque guidelines. Follow the pattern in the manual, and 44 in lbs first pass, 89 in lbs second pass.



Re-installed everything else, and bingo, it started right up!

Used the code reader to reset the code, drive it for a day to build history in the computer, and now ready to get emissions tested.

Hopefully cleaning the injectors and replacing the sensors will help it run a little better, every little bit helps given the price of gas.