You need an ABS capable scan tool ($2,000) to read the ABS codes. Probably a wheel speed sensor but being a MB it could also be a bad control unit with solenoids. I'd have it scanned at a dealer.
Basically, it means your ABS (anti-lock braking system) is malfunctioning and has shut down.
It can be caused by several things.
Low voltage to the ABS unit.
ABS unit failure
Damaged brake lines.
Damaged or dirty ABS sensors
You might wanna check that out because that light should be off
It means you have an issue with the ABS system. Most of the time it's one of the wheel speed sensors but the problem could be anywhere with the whole ABS system.
there is a problem with the ABS system ! check all the plug-ins going to the wheel sensors, one might be losing contact !
That means STOP driving until you fix your brakes.
2004 Mercedes-Benz C230