Biffle had just wrested second place from Michigan native Brad Keselowski when race leader Johnson lost his engine, setting up a green-white-checkered finish.
The Roush Fenway Racing team member turned back Keselowski's challenge on the final two laps to record a winning margin of 0.4 seconds, corralling his third career Michigan title.
He also moved into the points with his second win of the year.
Marcos Ambrose completed the Top 5.
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