After retiring as a player, Fach was appointed to coach the amateur team at Borussia Mönchengladbach (he worked with the club as a scout the previous year) and after a short intermezzo at Rot-Weiss Essen, on 21 September 2003 he became head coach for the former, leaving his post on October of the following year.
In January 2007, Fach took the reins of second division outfit SC Paderborn 07 (being fired midway through his second season). On 18 April 2008, he took over as manager of another second-tier side, FC Augsburg. After a disappointing beginning to 2009, FC Augsburg club management passed a vote of confidence in Fach for the remainder of the season, however both sides also agreed to end their cooperation at seasons end. On 13 April 2009, he was fired from FC Augsburg alongside with his assistant coach Dariusz Pasieka. After nine months without a job Fach was named on 25 January 2010 as the new head coach of the Kazakhstani vice-champion Lokomotiv Astana.