C0201
Brake Fluid Level Switch Circuit
The ABS or brake control module has detected a fault in the brake fluid level switch circuit. A low fluid level indicates a potential leak in the hydraulic system and disables ABS while a separate brake warning lamp is illuminated.
- Check engine light: Not always
- Emissions related: No
- Repair difficulty: easy
Symptoms
- ABS warning light on
- ESC/stability control deactivated
- Possible reduced brake assist
- Speedometer may behave erratically
Common causes
Ordered by how often each turns out to be the cause.
- Brake fluid level low (worn pads or hydraulic leak)Common
- Float switch in reservoir failedPossible
- Wiring or connector faultLess likely
Parts involved
- Brake Fluid Level Switch
- Brake Fluid Reservoir
- ABS Control Module
C0201 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.