After a run of four defeats in their last five Bundesliga games, the club has decided to relieve the Norwegian of his first-team duties and bring in the trainer who left last year
Solbakken only took charge of the Bundesliga outfit last May but has paid the price for a disastrous run of results which has seen the club drop to 16th in the standings.
Koln have now decided to turn to Schaefer, who walked away from the RheinEnergieStadion last April, leaving Volker Finke in charge on an interim basis before the arrival of Solbakken.
"Avoiding relegation from the top flight in the final stages of the season is our top priority," Werner Wolf, chairman of the club's board, stated.
"Stale Solbakken's leave of absence after the Mainz game is regrettable but inevitable at this time.
"For the sake of continuity, we have gone to our previous coach.
"Our team now needs a new impetus for the relegation battle. We thank Frank Schaefer for his willingness to take on this responsibility at such short notice."
Schaefer will be in charge when Koln lock horns with Borussia Monchengladbach this weekend.