I purchased the 2014 Honda Accord. When I make a left turn, I hear a knock sound. Any idea of what this could be?

check your brake caliper or tie rod ends

Take it back to the dealer since it should be under warranty.

Did you find out what the problem was? I have a 2014 Accord Sport with 750 miles and mine is doing the same thing.

The right front strut bearing was worn excessively. I asked how often should this be replaced on a Honda and the service guy said that it was very rare and he's never seen that happen on a new car. He said it was probably a defective part from the manufacturer when the car was made. It was replaced for free. The invoice says they replaced the right front strut bearing/spring seat and rubber mount, then they aligned front of vehicle. Hope this helps.

I have a 2014 Honda Accord sport making a roaring noise and gets louder when you slow down to stop. The car has 28k miles on the dealer replaced left front wheel bearing, no help. Dealer said left front tire was bad so I replaced it with the right rear tire, Did not change the front noise at all. The dealer doesn't have a clue. I wish I would have stayed with a Buick. This thing roars like a jeep with 33" mud lugs on it, you can hardly hear the radio. I believe the car is unsafe but the dealer says it's fine.

I had the same issue and it was the transmission specifically the torque converter.