having replaced knock sensors on different 1mzfe's 3 times now, i gave up on taking apart the entire intake and draining the coolant just for that on my own car. instead, i relocated the sensor and spliced the wires together to just use one sensor instead of two.
i got 2 sensors (in case one was bad, or to have a spare) and the short harness off a junkyard car. i split the harness, removed the plastic tubing that protects it, then cut off one of the leads about an inch from the 2x2 connector. there, i spliced the shields and signal wires together, then at the other end, i cut off the apparent 1-pin connector, and spliced on the rest of the wire that i'd cut off, to essentially double the length of the harness. keep in mind that this is COAXIAL wire - just like cable TV wire, but much smaller. so you can't simply cut/strip/crimp to extend this wire. you need to handle the outer shield and inner conductor independently and keep them insulated from each other. then i put the plastic wrap back on, and added a little more that i had so the whole thing was covered in the plastic shield.
i unplugged the existing knock sensor harness (pictured above) and plugged in my new harness, and draped it straight forward to the front of the engine, then a little left just below and in front of the oil filler cap. on my 98 there are two large empty threaded holes there (some may actually have a hanger bolted there, which is easily removed). i drilled and tapped one of these and screwed in my knock sensor, plugged in my new harness, then zip-tied the slack in the harness to keep it out of the way.
pull the EFI fuse for 30 seconds to clear the codes, and as long as you did good quality work on your harness extension, and your knock sensor is good, you're golden. now if it ever fails again, it's a 5 minute job to change. even with the harness work this still only took me 30 minutes. the hardest part was unplugging the old harness!
98 Camry CE v6 MT (formerly SC'd)
97 MX-5 (autocrosser/weekend car)
95 Camry SE v6 2dr SC (sold)