C004BBrake Fluid Level Sensor/Switch Circuit/Open
- Generic OBD-II code · Chassis
- Can trigger limp mode
- How the car detects it
- Covers an electrical fault, specifically an open or out-of-range circuit, in the brake fluid level sensor or switch, as opposed to C0049 which reports an actual low-level condition. The float switch or level sensor in the reservoir provides a defined signal to the brake or stability module; this code is set when that circuit is open, shorted or gives an implausible value so the module can no longer trust the level reading. Because the level warning is a safety function, the module may illuminate the red brake warning indicator and treat the level as unknown. A fault is usually a broken wire, a corroded connector or a failed switch rather than low fluid itself. Patents show the usual float magnet acting on a reed or Hall switch. No manufacturer documents this code publicly.
- What you may notice
- Red brake warning indicator on
- Brake fluid level reads as unknown
- Intermittent low-fluid warnings
- Likely causes
- LikelyOpen or chafed sensor wiring
- PossibleFailed level switch or float
- RareCorroded or loose connector
- Repair
- Easy · Often possible to do yourself.Typical cost: €20 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.