Langkow's end-to-end rush and backhand shot past Devan Dubnyk 4:44 into the second period broke a scoreless tie and Aucoin doubled the Phoenix lead with a power-play goal 13 1/2 minutes later.
Mike Smith turned aside 24-of-26 shots to earn the victory.
Rookie Ryan Nugent-Hopkins netted his sixth goal and Theo Peckham also scored for Northwest Division-leading Edmonton, which lost for only the third time in 14 games to start the season.
Dubnyk finished with 26 saves for the Oilers.
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