The Nigeria international has made 78 competitive appearances since joining Brentford from Midtjylland in the summer of 2021.
However, Onyeka was restricted to 13 starts in 28 matches last season and has had to settle for substitute appearances in Brentford's first two league games of the new campaign.
While Brentford have been open to Onyeka's departure, it was recently reported that they were yet to receive any offers for the midfielder.
However, German side Augsburg have now emerged as a potential suitor and are set to sign him before the transfer deadline
Onyeka set for Bundesliga move
According to The Athletic, Augsburg have reached an agreement with Brentford to sign Onyeka on a season-long loan deal.
There was a belief that the Bees were holding out for a permanent transfer, but have seemingly adjusted their stance at this late stage of the transfer window.
Augsburg will not have the option to buy Onyeka and they are now finalising negotiations before they can unveil Onyeka as their latest addition.
The midfielder still has three years left to run on his Brentford contract, with an option for the club to extend by a further year.