the cel went on and off on my car, so i took it to autozone and they told me the code for cel is p0325. and they also say some thing like the car might be running lean? but my car runs fine? it idels at 700 rpm when its warm and it runs pretty smooth. i dont know whats going on

so can some body please tell me whats going on, is it really my car is running lean? what are some of the sign for engine running lean? also if its just knock sensor malfunction, how would i fix it? please help!!!!!!!!!!!!!!!