1. Disconnect the brake fluid level sensor connector from the master cylinder.
2. Inspect for continuity according to fluid level between the brake fluid level sensor terminals.

If not as indicated in the table, replace the reserve tank.

Brake Switch InspectionJoint Shaft Removal/Installation [Skyactiv G 2.0]
CAUTION:
Performing the following procedures without first removing the ABS wheel-speed
sensor may possibly cause an open circuit in the wiring harness if it is pulled
by mistake. Before performing the following procedures, remove the ABS wheel-speed
sensor connector (axle side) and ...
Oil Pan Removal/Installation [Mzr 2.0, Mzr 2.5]
WARNING:
Hot engines and engine oil can cause severe burns. Turn off the engine and
wait until it and the engine oil have cooled.
A vehicle that is lifted but not securely supported on safety stands is dangerous.
It can slip or fall, causing death or serious injury. Never work ...
Before Service Precaution [Mzr 2.0, Mzr 2.5]
WARNING:
Fuel vapor is hazardous. It can very easily ignite, causing serious injury
and damage. Always keep sparks and flames away from fuel.
Fuel line spills and leakage from the pressurized fuel system are dangerous.
Fuel can ignite and cause serious injury or death and damag ...