The loco stands still or tries to move at very low speed? ESU decoders produce a certains buzzing sound in the operating motors, especially at low speeds, which is normal.
The coils are necessary because, together with the capacitor at the motor connectors, they "smoothen" the spikes that are produced by the rotating motor. When the locomotive stands still, at speed 0, the motor is not powered at all, so there should be no buzzing.
Buzzing mosquito sound coming from decoder when loco stand still, and also when its moving.
I have tried this via jmri
126.96.36.199 Adaptive Regulation Frequency
The decoder operates ex works with a mutable (adaptive) regulation frequency to drive the motor as precisely as possible. However, as a result some motors might show a nasty buzzing noise.
For such motors you are able to set the regulation frequency on a constant value. Set bit 4 to “1” in CV 124. How to manually set cv124 , current value is 24 (it have 4 bits) ?
and also tried this piko values from esu table, but same buzzing sound remains.