Arndt and crew Marko Huebenbecker, Alexander Roediger and Martin Putze were fastest in the first run and held on in the second to edge Manuel Machata's crew by 0.06 seconds with an aggregate time of 1 minute, 51.26 seconds.
Machata, Alex Mann, Jan Speer And Christian Poser were 0.33 seconds off the pace after a poor first run, but recovered with the fastest second to leave the other German team of Thomas Florschuetz, Andreas Bredau, Kevin Kuske and Thorsten Margis in third, 0.19 seconds back.
Latvia was fourth and the Czech Republic was fifth. Lyndon Rush piloted the lone Canadian sled to a sixth-place finish.
Rush, from Humboldt, Sask., and his Canada 1 crew of Jesse Lumsden of Burlington, Ont., Calgary’s Lascelles Brown and Edmonton’s Neville Wright finished with a two-run time of 1:51.97.
With three races remaining, Arndt has 1,139 points in the standings, 29 more than Russia's Alexander Zubkov, who didn't race. Machata is third with 1,074.