Sieg's suspension was announced Monday. He's the second driver from NASCAR's top three national series to be suspended since the random drug testing policy was adopted in 2009.

Jeremy Mayfield was the first driver suspended. He failed a random test in May 2009. He's currently suing NASCAR over the suspension.

Sieg has run in 12 of the 15 Trucks Series races this year. His season-best finish was 12th at Darlington in May.

He last raced at Pocono on Aug. 7, finishing 14th.

Sieg did not race at Michigan last Saturday.

NASCAR also announced Monday it has reinstated Nationwide Series crew member Denise Harmon-Mixon after successful completion of a rehabilitation program.