Brakes suddenly failed in the middle of driving causing a major safety hazard. There was no warning. Went to the dealership and was diagnosed âBrake - Fluid Accumulator: INSPECT AND FOUND CODE C1391, ABNORMAL LEAKS IN ACCUMULATOR, RECOMMEND TO REPLACE BRAKE BOOSTER, MASTER CYLINDER AND PUMP. The brake fluid accumulator is a part of the Anti-Lock Brake System. The accumulator stores brake fluid under pressure from the ABS Pump and can instantly provide fluid under pressure to the brakes.â It appears this issue is not an isolated incident and others with the same or similar year/model have had this issue. It is extremely dangerous that the brakes suddenly failed to function without warning. The brake pads and brake fluids were adequate and the vehicle was up-to-date on regular inspection and maintenance.