Brake Fluid Level Sensor
A float switch in the brake fluid reservoir that lights the red brake warning lamp when the level falls below minimum.
It is the cheapest part on the car with a genuine claim to saving lives, because the fault it warns about — a hydraulic leak — ends with the pedal going to the floor and gives almost no other warning.
A low reading has two very different meanings and telling them apart takes a minute. Pads wearing down draw fluid into the calipers, so the level falls slowly and legitimately over the life of a set, and returns when new pads push the pistons back. A leak is the other explanation, and it does not recover.
Do not top up and carry on. Topping up hides the only warning the system gives, and on worn pads it causes the reservoir to overflow when the pistons are pushed home at the next pad change.
The switch itself fails rarely — more often the connector corrodes, or the float sticks in a reservoir whose fluid has gone dark with age.
Also known as: brake fluid level switch, reservoir level sensor, brake fluid sensor, fluid level float switch
Referenced by 2 codes
Codes involving this component (2)
Other components in Braking, Steering and Suspension
- Brake Booster 92
- Wheel Speed Sensor 72
- ABS Hydraulic Modulator 69
- Brake Pressure Sensor 42
- Tone Wheel 39
- Yaw Rate Sensor 28
- Brake Pedal Position Sensor 23
- Steering Angle Sensor 21
- Electric Power Steering Motor 13
- Ride Height Sensor 7
- Tyre Pressure Sensor 5
- Electric Park Brake Actuator 4
- Park Brake Control Module 4
- Air Suspension Compressor 3
- Brake Pad Wear Sensor 2
- Traction Control Switch 2
- Brake Caliper 1
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