Nissan Repair: Altima 97 sensor code error, crankshaft position sensor, nissan altima

Question
Hi,
I took my car 97 Nissan altima today at AutoZone to find out why check engine light is coming and they told me it’s because of 2 sensor code. 1) Knock sensor 2) crankshaft position sensor. My question is does those 2 sensor effect poor mileage because in full tank its giving me 150 to 180 miles only and my other question is. Is  it easy to replace by my self or do I have to take it to certified mechanic
Plz help me thank u very much  

Answer
Zafar,

The knock sensor is on the engine by the intake and the crank position sensor is on the timing cover.  Both are easy to do if you have metric sockets.  After you replace them you can clear the code by disconnecting the battery for a few minutes or take the car to Autozone and have them clear the codes.