When the
brake booster fails, the braking pressure needed at the brake pedal increases dramatically, and, in some cases, the brakes may seem unresponsive. For vacuum boosters, failure will generally create a vacuum leak, and the vehicle may run roughly, become hard to start, misfire at engine idle, and exhibit poor fuel mileage. The check engine light may also illuminate, and OBD trouble codes for engine misfires, lean air/fuel mixture, and intake manifold pressure will be stored in the computer. If the brake system uses they hydro-boost system, there will likely be a power steering fluid leak on the ground, and the brakes will be very difficult or impossible to press.
