Howell, the defending champion, was joined in the lead by Martin Erlandsson, Gary Evans and Garry Houston.
Lee Westwood, who is trying to play his way onto the European Ryder Cup team, carded a 4-under-par 68. He shares fifth place with Luke Donald, whose spot on the European team is safe, Jose-Filipe Lima, Matthew Millar, Marcel Siem, Peter Hedblom, Bradley Dredge and David Drysdale.
European Ryder Cup captain Ian Woosnam, who opened with a 4-over 76, will select his two captain's picks on Sunday after the completion of this event.
Howell, who was paired with Donald and Woosnam, played the back nine at Golfclub Munchen Nord-Eichenried first on Thursday. He played his first nine at even-par with a birdie on 11 and a bogey at 15.
The Englishman birdied the par-4 third to get back into red figures, then turned it on down the stretch. He dropped in a birdie putt on the seventh and made it two in a row as he also birdied the eighth.
Howell's second shot to the par-5 ninth stopped within 10 feet of the cup and he rolled in the eagle putt to play the last three holes in 4 under par.
'I thought I was playing quite nicely today. I hit a couple of bad tee shots on the par-5s, but other than that I played nicely,' Howell stated. 'It didn't seem like it was going to be my day at all and then a nice 8-iron to about 10 feet on seventh. I rolled that one in.
'Then a 5-iron to probably 15 feet on the next hole. Then that was the first eagle I made in a long time at the last. So I was delighted to have shot 67 at the end of the day.'
Howell has been struggling as of late. His last top-10 came in late May when he won the BMW Championship at Wentworth.
'I wasn't looking forward to today too much after the way I played in the pro-am Wednesday,' Howell admitted. 'My form hasn't been great for a couple of months now. I don't mind admitting that. I was delighted with the way I struck the ball today.'
Erlandsson, like Howell, played in the morning wave and also started on the back nine. He was minus-1 through nine with two birdies and a bogey. The Swede ran off four consecutive birdies from the third to join Howell in the lead.
Evans, the only of the four leaders to play the front nine first, birdied three and four to get his round going. After faltering to a bogey on the ninth, he birdied three of the next four to get within one of the lead. Evans birdied the par-5 18th for his share of the lead.
Houston carded his lone opening-nine birdie on the par-4 13th. He parred five in row from there. The Welshman dropped in a birdie putt on the par-3 second. He then birdied three of his final four holes to get to minus-5 and close a bogey-free round.
Darren Fichardt, David Lynn and Mikko Ilonen are among 11 players tied for 13th place at 3-under-par 69.
Among those trying to play their way onto the European Ryder Cup team are Thomas Bjorn (minus-1, tied for 43rd) and John Bickerton (plus-1, tied for 80th), while Paul Broadhurst and Johan Edfors are tied for 62nd at even-par.