The 29-year-old, who has 15 caps to his name, missed out on Euro 2012 in the summer with a persistent groin problem.
"To be honest, I have missed nearly a year now since I last played with injuries and I am desperate to play, I am desperate to play for Ireland," said Fahey. "I am not one who comes and expects to sit on the bench every game, I want to play.
"If I have to do better in training or whatever, I am willing to do it. I want to play, I want to get more caps under my belt, I want to do well. I want to wear the green shirt.
"In the summer, I dropped out and someone else came in. In football, someone's loss is someone else's gain, so maybe there will be opportunities for lads to step in and get a chance to play. Playing three against the quality of Germany is going to help the team be more solid."
Ireland host Germany in a World Cup qualifying match in Dublin on Friday.