One problem related to engine knocking noise has been reported for the 2015 Nissan Sentra. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2015 Nissan Sentra based on all problems reported for the 2015 Sentra.
Car has been making tapping/knocking/squealing noise since about 20,000 miles. Dealership was notified, as well as Nissan consumer affairs. (audio was taken of noise). Car was taken to shop. Mechanics could not "replicate sound" that my car was making, even though I had shown mechanics proof, and they heard car making noise at idle and when car was revved up. Mechanic was instructed to take car home for a period of 7 days. He could not "replicate sound" that my car was making. My car had been in and out of the shop (for the same issue) at least 6 times between 2016-2017. And the issue still remained. Now (40,000+ miles since noise first started), I have noticed a significant reduction in horsepower, coupled with the squealing/tapping/knocking noise, that is progressively getting louder. I once again have contacted Nissan consumer affairs, who instructed me to take it to a different Nissan repair facility and front the $99. 00 diagnostic fee to have my vehicle diagnosed. I am now without a vehicle, and I still am in the dark as to what is going on with my car. The sound that my car makes occurs when my car is moving, idling, in gear, or in park. I have notified the dealership and consumer affairs of this ongoing issue, and feel that they just do not want to look into this, even though there is an issue with my car.