Mercedes-Benz: Primary Brake System

Hybrid vehicles equipped with a vacuum pump may experience internal component failure due to insufficient durability of internal parts. As internal components deteriorate during use, the pump loses the ability to generate negative pressure. Continued operation under this condition results in insufficient negative pressure, preventing proper engine control and illuminating the engine warning light while activating fail-safe mode control. In the worst case, exhaust emissions may exceed regulatory limits. Additionally, the decrease in negative pressure may cause the brake warning light to illuminate.