A rear tail light housing can fail causing the brake light on the affected side to be inoperative. Replacing the failed housing is commonly required to correct this issue.
Car Problem Reports
Mercedes-Benz C280 Brake Lights May Not Operate Due to Failed Rear Tail Light Housings
Mercedes-Benz C280 Problem
Average Mileage: 124,000 mi (74,000 mi - 147,000 mi)