Can you drive with a bad knocking sensor?

Sure, assuming that you know your knock sensor is bad because the check engine light told you so. The computer makes adjustments to compensate for not having correct information from this sensor and you may see your fuel mileage and performance suffer.

If you have standard mechanics hand tools, you can change this yourself in a few minutes. I think I paid around $25 on-line for a new one.

Knock sensor is accessed from the top of the engine from the driver's side and below the intake manifold. It is a small black donut shaped device less than 2" across with a capscrew through the middle. Screw is oriented vertically. You will want the engine to be cool while you are doing this so you don't burn yourself. As I recall it took a 10mm socket, extension, and ratchet. Squeeze and pull the electrical connector to disengage. Car fixing difficulty on a scale of 1 to 10 I would put at a 2.