92 lumina z34 Knock sensor?

Okay so i have a knock sensor thing wrong, Says my car when i did the paper clip thingy with the computer lol :P
What i need to know is... what i need to know is how i would look into this would i have to take it to my mech. or can i simply just do it myself on the street???
thank you

Oh sorry ALSO!.. does this effect my gas mileage because that is poor also

so nobody can answer this for me?

knock sensor will not affect gas mileage. and it is located "facing the car" passenger side, upper engine area, below center of intake manifold, mounted in engine block...
to improve gas mileage, try some of the following:
clean air intake and make sure passages are free of any obstacles. clean tps, iac, pcv, egr, vacuum lines, test o2 sensor and map sensor, new fuel filter and be sure all injectors are working properly. these are beyond the usual oil changes and tranny flushes. if you still get poor mileage, try using higher octane fuel and check your manifold gaskets...
oh, and clean your upper intake. being a 92 "like mine", its probably in dire need of it. also be sure your converter isnt plugged up as well. I bought a new one "magnaflow", along with flowmaster mufflers, love the sound...
if you have any probs, email me and ill give ya my tel number, ill help as much as my knowledge will allow. in fact, anyone else with the 92 z34 wants to shoot the sh*t about the car, feel free to email me. i'd love to hear about more ideas...