I removed the intake manifold, and my knock sensors are not there. Can anyone tell me where they ar located on 2000 lexus es 300.

You have 2 of them,here's a link showing where their at,once you get to page,click on switch and relay. SENSOR KNOCK CONTROL 176 07 Fits LEXUS RX300 1993 2005 Part 8961512090... Here's a video showing you where they are at. 2000 Lexus Es300 Knock Sensor Location Repair

here is a video showing the replacement of your knock sensor. it is located under the intake manifold. http://www.youtube.com/watch?v=bDSmfxb1o1E

the knock sensors are located underneith the intake manifold on either side of the engine block. you have 2 of them

there may be two of them, one on each side of the lower part of the block,

Your vehicle is equipped with 2 knock sensors. They are located on the cylinder heads under the intake manifold. They look like the picture below.

NOTE: Most knock sensor codes are caused by mechanical problems with the engine like pullies that are "rattleing" or lifters that are "tapping" etc. The knock sensor does not know the difference between "ignition ping" and mechanical problems like those mentioned. Knock sensor codes set when the engine computer has retarded the ignition timing as far as it can in an effort to stop ignition ping and the knock is still present. This is usually because the problem is not caused by ignition ping.

remove intake manifold and air intake chamber completely, the knock sensors are located in middle of engine

yes, I have they are located between the 2 banks of the motor. you need to remove the upper intake manifold to get to them. not hard to do. Also its a good idea to replace the mini harness with them.

Need to remove the upper and lower air intake manifold.  There are two knock sensors for the front and rear pistons banks.  If you plan to do this yourself it is about 1 to 2 hours.  While you are at it, there is a short coolant bypass hose sitting in the same spot, replace it.  Another problem with the knock sensor is the wire harness used to connect the two knock sensors into one connection sometimes wears out and contacts the metal on the engine causing false signals to the ECM, so replace this cable also.
Just did this last summer on my 99 ES300.  Pretty easy.
DIYr

1. located on top of engine below intake manifold

knock sensors are underneath the lower intake. replace the knock sensor harness as well