2011-12: Christoffer Ehn skated for the Skovde IK club in western Sweden near his hometown of Skara and played for Vastergotland in the 2012 TV-Pucken tournament for high school players. He scored 4 goals and was +2 with 4 penalty minutes in 14 games for the Skovde IK U20 team. Ehn scored 7 goals with 4 assists and was minus-28 with 16 penalty minutes in 25 games for the Skovde IK U18 team. In eight games for Vastergotland he scored 5 goals with 7 assists and was +13 with 2 penalty minutes.
2012-13: Ehn went from Skovde to the powerful Frolunda club; skating for the U18 squad. He scored 9 goals with 22 assists and was +22 with 16 penalty minutes in 33 regular season games and had 1 goals with 2 penalty minutes and was +1 in three playoff contests.
2013-14: Ehn made his pro debut in the SHL as a 17-year-old — appearing in two February games with Frolunda with no points nor penalties — and spent most of the season with the club’s U20 team. He represented Sweden in international play for the first time — skating for the U18 team at the 2014 World Junior Championship in Finland. In 48 games with the Frolunda U20 team, including three playoff games, he scored 7 goals with 7 assists and was minus-6 with 14 penalty minutes. Ehn scored 8 goals with 10 assists and was +15 with 4 penalty minutes in 15 regular season games for the Frolunda U18 team and had 1 goal with 3 assists, finishing +1, in five playoff games as the club captured a bronze medal. In seven games for fourth-place Sweden at the WJC he had 3 assists and was -1 with no penalties. Ehn was ranked 89th amongst International skaters in the Central Scouting final rankings and was selected by Detroit in the fourth round (106th overall) in the 2014 NHL Draft.
2014-15: Ehn saw limited ice time for Frolunda’s men’s team and captained the club’s U20 team. He appeared in four games on loan to Oskarshamn in Allsvenskan and played for the Sweden U20 team at the 2015 World Junior Championship. Averaging under three minutes of ice time in the regular season, he had an even plus/minus with no points and 2 penalty minutes in six games as Frolunda finished second. In seven playoff games Ehn was -2 with 2 penalty minutes, averaging 8:42 of ice time. He had no points nor penalties for Oskarshamn and scored 12 goals with 24 assists and was +10 with 61 penalty minutes in 40 regular season games for the Frolunda U20 team. Frolunda finished first in the SuperElit South Division. Ehn had 2 assists and was -1 with 2 penalty minutes in seven games for Sweden at the WJC. Sweden finished fourth, falling to Slovakia, 4-2, in the bronze medal game.
Ehn thinks the game well and is very sound defensively. He has a big frame that will take time to fill out. He is a two-way centerman, though the offensive side of his game is still very much a work in progress. Ehn skates well for a player his size.