ancdmd

On my 2002 LS with 127k miles I have a persistent engine knock and think maybe the knock sensor(s) are not operating properly. I've always used premium quality fuel and have recently run 5 bottles of Lucas Deep Fuel System Cleaner through 5 tanks of fuel with no alleviation of the knocking. MAF and TB are clean, plugs are new. Exhaust inspected ok. Never thrown a CEL.

How difficult is it to replace one or both of the knock sensors?