Brake Fluid Level Sensor Circuit Malfunction
What does C0100 mean?
The C0100 code means the vehicle's onboard diagnostic system has detected: Brake Fluid Level Sensor Circuit Malfunction. This is a critical severity code.
Common Symptoms
- Brake warning light on dashboard
- Low brake fluid warning message
- ABS and traction control lights on
- Brake fluid level reads incorrect
- Warning light on but fluid level appears normal
Probable Causes (Ranked by Likelihood)
- Low brake fluid level due to worn brake pads Very High
- Faulty brake fluid level sensor in reservoir High
- Brake fluid leak in system Moderate
- Corroded sensor connector Low
Step-by-Step Diagnostic Procedure
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Visually check brake fluid level in master cylinder reservoir
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Inspect brake lines and calipers for leaks
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Check brake pad thickness at all wheels
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Test fluid level sensor by raising and lowering float manually
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Check sensor connector for corrosion
Frequently Asked Questions
Why does brake fluid drop when brake pads wear?
As brake pads wear thin, the caliper pistons extend further out, taking up more fluid from the reservoir. This is normal and the fluid level will drop as pads wear.
Should I just add brake fluid to fix this?
Only add fluid after checking for leaks and inspecting brake pad thickness. If the fluid is low because pads are worn, adding fluid without replacing pads masks the real problem.
Is a brake fluid leak dangerous?
Yes. A brake fluid leak can lead to partial or complete loss of braking ability. If you see fluid on the ground or a sudden drop in the reservoir, do not drive and have the vehicle towed.