[john walker's workshop]

the fuse powers the relay, which powers the o2 computer, which operates the frequency valve, which makes the engine run properly. it does not actually power the o2 sensor. the o2 sensor just gives signals to the computer so it can adjust the speed of the of the frequency valve. unplugging the o2 sensor when everything else is working properly takes away the surge when cruising, and gives a better, smoother idle, especially when set to around 3% CO. it's kind of an add-on system that you can live without, except for the emission test.