Check Brake Fluid Level

WARNING: This page is about a different car, the 2011 Nissan Leaf. However, it is still accessible from the selected car via links, so may be relevant.

Check that the brake fluid level in the reservoir tank is within the standard (between MAX - MIN lines).
Visually check around the reservoir tank for brake fluid leakage.
If the brake fluid level is extremely low (below the MIN line), check the amount of brake fluid and check for brake fluid leaks in the brake system.
Check for dirt or other foreign material inside the reservoir tank, and check that no oil other than the designated brake fluid has entered the system.