Haynes Repair Manual - Toyota Tundra & Sequoia 2000 thru 2002 (I have an '01 Sequoia) states in Chapter 6 page 8;
Drain the engine coolant and remove upper and lower intake manifolds.
Disconnect knock sensor electrical connector.
Unscrew the knock sensor with a deep socket.
Installation is the reverse of removal, be sure to torque to specs (which is 33 ft/lbs).
Never having removed and reinstalled the upper and lower intake manifolds I can't say whether the estimate is reasonable or not. I'd certainly try to rule out other causes before changing out the knock sensor and finding out the code is still showing up.
On the AC fan, unrelated to code. My Sequoia when set on "Auto" the fan finds a speed that resonates and is quite loud. I adjust the speed either up or down a bit and it quiets down. Likely a bearing in the fan motor is getting old and loose and may need to be replaced someday. For the moment changing the speeds works on mine.