207 Humming in 4 and 5 gears

Friends, I bought the 2007 model vehicle y15 days ago, the thing that draws my attention is that I put the car in 4 gear, a hum comes, then I throw it at 5, the hum goes on. lit antipollion gave a malfunction, frankly I did not know what this buzz was.

actual

The buzzing sounded like a situation to me about the gearbox. It is necessary to have your oil checked. Has there been any change in the pressure pad recently? Antipolution may have made the fault warning from a fuel change.

It's like the noise of the wind coming from the engine, but the vehicle does it quickly