Brake fluid is highly corrosive and dangerous to the environment, so it must be disposed of properly. When working at the brake fluid reservoir located at the left rear of the engine compartment, detach the brake fluid level sensor connector and remove the reservoir cap. Use a clean syringe to empty the brake fluid reservoir, then disconnect the DSC precharge pump supply line from the fluid reservoir, being prepared to catch any dripping fluid and securing the supply line in a vertical position to prevent excessive fluid loss. Plug open brake fluid lines and ducts to avoid leakage and contamination, then remove the brake fluid reservoir by tilting it sideways. Disconnect the brake master cylinder brake lines and plug them to prevent contamination, then remove the brake master cylinder by taking off the mounting nuts. During reinstallation, ensure that all nuts, fluid couplings, thread bores, and mating surfaces are clean. Mount the brake master cylinder to the brake booster using a new sealing O-ring and new self-locking nuts, making sure to align the brake master cylinder pushrod and booster pushrod. Avoid over-torquing the mounting nuts to prevent damage to the brake booster and ensure proper vacuum build-up. Connect the brake fluid lines to the brake master cylinder, reinstall the fluid reservoir with new sealing grommets, and reconnect the precharge pump fluid supply hose if applicable. The remainder of the installation follows the reverse order of removal. Finally, top up with fresh brake fluid and bleed the entire brake system.