The Aubach rises north of Wendershagen, at the Heckenweiher, approximately 414 metres (1,358 ft) above sea level. It initially flows in a north-westerly direction. Not far from Erdingen, the Aubach merges with the Mohrenbach, which is about 1 kilometre (0.62 mi) long, then turns to the north-east. In the Pfänderwiese, another tributary, flows from the left into the Aubach. Further to the north, the Aubach reaches the Aubachtal.
The right source stream, also called Schönbach, is about 1 kilometre (0.62 mi) long. It rises in Schönbach, on Rhineland-Palatinate territory, at approximately 395 metres (1,296 ft) above sea level. It continues in a north-easterly direction until the Aubach reaches Wildbergerhütte. There, it unites with the approximately 1.8 kilometres (1.1 mi) long Wildberger stream. It rises in Wildberg to about 382 metres (1,253 ft) m above sea level, and is additionally fed by the roughly 1.2 kilometres (0.75 mi) long Langenbach. The Aubach river then turns north-west and reaches the centre of Wildbergerhütte, along the pond dam. At about 311 metres (1,020 ft) above sea level, the Aubach flows into the Wiehl, after about 3.2 kilometres (2.0 mi) (4.2 kilometres (2.6 mi) with Möhrenbach) to the sports field in Wildbergerhütte.