C0128
Low Brake Fluid Indicated
The brake fluid level switch in the master cylinder reservoir reports a low level. ABS and stability control may be deactivated as a precaution.
- 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.
- Worn brake pads (fluid drops as pistons extend)Common
- Hydraulic system leakPossible
- Level switch failedLess likely
Parts involved
- Brake Fluid Level Switch
- Master Cylinder Reservoir
C0128 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.