This excerpt from the user's manual can explain the problem of your motor.
"... Do not use corrosive, acidic or alkaline detergents. Switch the unit back on by plugging in the unit or by activating the safety switch. en 20 Caution before installation Exhaust air mode Exhaust air is discharged upwards through a ventilation duct or directly through the outer wall to the outside. - - - On the installation side, provide a switching option with a contact opening width of at least 3 mm with which the device can be switched off. Connecting the cooktop and hob - Check that the voltage indicated on the rating plate corresponds to the available mains voltage. ~ ~ ~ - Connect the two 3- and 4-pin connectors on the cooktop to the corresponding sockets on the stovetop...."
NEFF B55CR22N0, NEFF E15M63N3, , NEFF MEGA EM 1242 N, NEFF B58VT28N0B, B58VT28N0B