If the knock sensor is in the same place as my '92, it'* a bitch to get at. It'* located at the right rear of the block, up high close to the valve cover. It'* above the oil pressure sending unit. One way to know which one is that it has only a single wire running to it.
If you take off the right front wheel and remove the floppy shield, you can see it, but to get it out it'* best to go from underneath.
I have seen and read a lot about the threads being dirty, and even the manual says that the threads should not have anything on them, but my new one came with a sealant already on the threads, and I found that the sensor plugs up an oil passage. So I guess the theory is that even with a sealant you will get an electrical connection to the block.
1992 green ssei. Tan leather, moonroof, power everything. 161k miles
Goodyear RSA Plus 225/60/16 VR on chromed factory crosslace rims. McGard chrome lugs.
Audio system: CD player w/equalizer, subwoofer (all stock).
Delco premium wires, NGK TR55 plugs, K&N stock style air filter. Ceramic brake pads. New rear brake tubing and proportioning valves. New wheel cylinders, front rotors and calipers. New front wheel bearings. Replaced crank sensor and harmonic balancer. Rebuilt instrument cluster. Cleaned A/C evaporator. Valve cover gaskets. Alternator. Front stabilizer links. Replaced all power steering lines and transmission lines. Cleaned MAF and IAC. New door appliques. Rebuilt steering gear. CERAMIC brake pads, I love them. I am listing all this in case someone needs advice on any of these repairs.