code 43

i pulled a code 43 on my 93 blazer and the sheet i have says that a code 43 is that the knock sensor signal was ether above 3.5 volts or below 1.5 volts for at least 20 seconds. i need to know what a knock sensor is, where it is, and if I can replace it myself.

You can replace it yourself... The knock sensors monitor vibration, knock, et-al (hence the name) and adjust the computer controlled timing as needed. You will have one below and between the 1 and 3 plugs, and one pn the passenger side head against the firewall. They are both different part numbers so take the one you are replacing in with you when you go to the autoparts store. Most times the guys don't understand the difference. Just be warned, when you pull the driver's side one you will loose coolant.