Lexus Troubleshooting Questions? Ask a Lexus Expert
The knock sensors are under the lower intake. Here's pictures of the sensor location and the wiring diagram. You have to trace the wires to find their locations.
Theres two sensors under the intake. One is on the front cylinder bank of the engine and the other is on the rear cylinder bank under the intake. The wires go out under where the throttle would be. The sub harness starts under the throttle and goes to the two sensor. I have replaced the senors and harness more times that I can count and have never found a fault in the main harness in relation to the code you have. I always just do both sensors and the harness because only the sub harness goes bad and the sensors go bad one at a time so you might as well do both.
Here's a picture of the sensors in relation to the block. I drew a red line where the harness comes out.