What a pain I have been through the last few months. I had been getting code for knock sensor and even after replacing, still had code. I wanted to share what I learned in the hopes of helping the next guy who ran into this.

1- Before doing the job of changing the knock sensor, pull the cover off of the computer right by the battery. Disconnect the negative battery cable and disconnect the 2 plugs using a 7mm socket. Inspect the terminals on both the computer side and the plug. Any signs of water damage and you will need to clean the terminals REALLY well. With the computer disconnected, use some CLR and a toothbrush (may need to grind the sides of the toothbrush down to fit). Brush the terminals well, should foam up a bit removing any corrosion. Then spray the part you cleaned with brake clean or electrical contact cleaner, blow dry with compressed air. Pins are sealed from computer internals by epoxy so no need to be worried that anything will get inside. For the plug side, remove the plue plastic protector with a pick. Get a pack of oral proxy brushes from the pharmacy, Again using CLR, pour a bit into each pin that may have been corroded and use proxy brushes to clean the inside of the connector. Again spray with Brake cleaner or Electrical contact cleaner and blow dry. Before actually reinstalling the computer, disconnect the knock sensor plug at the back of the intake manifold and using an electrical multimeter, check for continuity between the knock sensor plug and the computer plug. On my 02, the pins were 11 and 51 on the blue plug but your model may differ. If no resistance and continuity is good, you can be confident that you have either a bad knock sensor or a bad computer. On to the next step....

2- If you are sure that no wiring problem exists, you need to replace the knock sensors. DO NOT BUY FROM AMAZON OR EBAY!!!!!! Although much cheaper, I ended up with 2 defective knock sensors. I also noticed that AC delco part from Ebay looked different from part purchased at the dealer. Part from the dealer was crimped/notched between the top plate and the threaded body. This is only a hypothesis but the fact that I ended up with 2 bad sensors after buying from 2 different Ebay suppliers leads me to believe that those may have come from questionable lots and maybe that's why they were so cheap. BUY FROM THE DEALER!!!!!! You will also need the knock sensor wire harness, this is a must!!!! Also get intake manifold gasket set. DO NOT DROP THE KNOCK SENSOR!!! They are very fragile, if it fell, throw it away and get another one!!!!

3- Time to replace BOTH knock sensors. Remove intake manifold. Not that big of a deal, you need a screwdriver, 7mm and 10mm sockets with a universal and an extension, a 10mm wrench and a torx screwdriver. Videos show how to do this on Youtube but ultimately you are removing the intake manifold. No need to disconnect fuel injectors, fuel rails, vacuum lines or wire harnesses, everything gets disconnected and pulled off to the side. When you have the manifold off, remove the knock sensors and knock sensor wire harness and throw them away. Get a dremel and a tiny wire brush attachment that will fit in the hole. Clean both holes with the dremel wire brush and the spray in some brake cleaner, blow dry the 2 holes. LOOK INSIDE WITH A LIGHT!! Make sure both holes are clean. Install the new knock sensors HAND TIGHT!!!!. No sealant or anything else!!! Sensors MUST BE TORQUED EXACTLY!!!!! Using a 3/8 torque wrench, tighten to exactly 15ft lbs. Now, time to install the harness, pull back the rubber boots some and push the plugs on firmly. Time to check our work. Get the multimeter and check for continuity between the body of the sensors and the negative battery cable. If you have cleaned the inside threads as previously discussed, they should be perfectly grounded, no resistance whatsoever. Now lets check that the sensors are good. Put 1 lead from the multimeter in the top of the sensor and the other to the negative battery cable. Good sensors read about 100 ohms. If your reading differs, you may have a defective sensor. If all went well, now it's time to seal the boots, using a bead of silicone around the belly of the sides of the boot, push down firmly into hole pulling the wire up so we don't kink it installing the boot. when the boot is all the way down you should have some silicone oozing out from the sides, smoothen it out to be sure that nothing can get into knock sensor cavity. Now put some silicone around the wire where it enters the boot so that we are sure that water cannot get in there.Once again check for resistance of each sensor to be sure you didn't mess up the connection while siliconing and enclosing the plugs. The harness sits on top of the engine. I didn't like that, it may get hot and dry out and crack over time. This is optional but I didn't ever want to have to do this again so I took a piece of foam and tie wrapped the sensor wire to the foam so that the wire that sits between the 2 sensors cannot touch the top of the engine and get hot. As for the wire where it comes out at the back of the intake manifold, I wrapped it in another piece of plastic looming and lots of electric tape, then I tie wrapped it to the wiring by the firewall to ensure it would not get pinched by the intake manifold. I cut a little bit of the foam material that sits in the cavity under the manifold so that it would not get squished by the manifold. After placing the intake manifold (with new gaskets) on the engine, make sure the harness is in the notch that you cut out of the foam.

4- After putting the car back together, clear the codes with a scanner. Now it's time to see if the problem is solved. Take the car on the highway for 15-20 minutes and recheck for error codes. If you are still getting the code, you need to order a replacement computer. They are available reconditioned on Ebay relatively cheaply (mine was about $100). Programming is about 30 minutes and requires a battery charger,.

I went through every possible issue mentioned above, Drove me nuts!! I had bad knock sensors, corroded wire connections at the computer, a bad computer and finally 2 defective knock sensors. My car is finally fixed but I had to spend ALOT of time to get it there. Best of Luck!!!!

 

And dont forget to use dialectrical grease on all the connectors too. Cheap insurance to be sure.

 

you cannot use dielectric grease on connections to computer, where I did use it was on the gaskets for the computer plugs to help prevent any water from getting in. The other connections I guess it would be okay but probably not in the knock sensor itself. Voltage produced is millivolts and dielectric grease is not a conductive so it could mess with the readings.