C0128Low Brake Fluid Indicated
- Generic OBD-II code · Chassis
- How the car detects it
- C0128 is not part of the accessible J2012 tables. GM lists it among its chassis codes in bulletin PIP5094, and the GM-based ABS table published by AA1Car words it Low Brake Fluid Circuit Low. The input comes from the level switch in the master cylinder reservoir: a float carrying a magnet closes a reed contact once the fluid drops, as patents from ITT and from Nabco/Nissan show. FMVSS 135 requires the red brake warning to light when the level falls below the maker's safe mark or a quarter of a compartment, whichever is higher. A genuinely low level usually means worn pads or a leak and calls for a brake check before driving on; a full reservoir with the code points to a stuck float, a shorted switch or chafed wiring.
- What you may notice
- Red brake warning lamp or low fluid message
- Possibly longer pedal travel if fluid is really missing
- Likely causes
- LikelyFluid level genuinely low from pad wear or a leak
- PossibleStuck float or shorted reed switch in the reservoir
- RareChafed switch wiring shorted to ground
- Repair
- Easy · Often possible to do yourself.Typical cost: €10 – €400
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.