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 InspectionGenerator Removal/Installation [Skyactiv G 2.0]
WARNING:
Remove and install all parts when the engine is cold, otherwise they can
cause severe burns or serious injury.
When the battery cables are connected, touching the vehicle body with generator
terminal B will generate sparks. This can cause personal injury, fire, and ...
Air Intake Actuator [Full Auto Air Conditioner]
Purpose
The air intake actuator moves the air intake door in the blower unit to switch
the air intake port.
Function
The air intake actuator drives the motor based on the signal from the climate
control unit and moves the air intake door to the FRESH or REC position.
...
Camshaft Position (CMP) Sensor Inspection
Intake CMP Sensor
Visual inspection
CAUTION:
When replacing the CMP sensor, make sure there is no foreign material on
it such as metal shavings. If it is installed with foreign material, the sensor
output signal will malfunction resulting from fluctuation in magnetic flux and
caus ...