first question, how can you tell that u need a new knock sensor? my car sometimes hesitates when i accelerate, only in first and 2nd gear. is that a side effect of a worn out knock sensor? secondly can u just buy it at an autoparts store, or is it a dealer part from nissan? thanks for the help

 

Check for ghost codes or check the voltage.

There are Nissan knock sensors and aftermarket ones (like Bosch) that you can probably get from the store. Check eBay

 

search. there are a zillion threads on this.

 

Search before I'm forced to ban you.