Front pads are likely cooked. When they are just beginning to run on the wear sensor, the warning light can be intermittent.

Good luck, and make sure your brake fluid is no more than 3 years old!

__________________
"If God had meant for us to walk, why did he give us feet that fit car pedals?" Sir Sterling Moss

Michael
2014 E63S Estate
2006 SLK55
1995 E500
1986 Porsche 944 turbo