The 2020 Sierra 2500HD/3500HD may have a whistling sound coming from the front of the vehicle while driving. (Fig. 29) The intermittent sound is most commonly heard when the vehicle is traveling 50 mph (80 km/h) or higher and is also affected by the strength of crosswinds.
Fig. 29
The cause of the whistling sound may be air turbulence under the front edge of the hood. If this condition is found, replace the hood front edge weatherstrip and molding with updated service parts. (Fig. 30)
In order to remove the hood front molding, the hood ornamentation vent also must be removed. Refer to Hood Front Molding Replacement in the appropriate Service Information.
Fig. 30
Refer to Bulletin #20-NA-035 for additional information and part numbers.
– Thanks to Kevin Minor
A sound file would have been helpful in this information