C0258Brake Booster Vacuum Sensor Circuit
- Generic OBD-II code · Chassis
- How the car detects it
- No public record of C0258 exists: the publicly available J2012 lists, the NHTSA bulletin index and the GM and Saab indexes all lack it. Only the sensor named in the title can be described. A booster vacuum sensor tells the control unit whether enough vacuum is stored for power-assisted braking; GM needs it on cylinder-deactivation engines, which return to all cylinders when vacuum gets low. GM patent US7076347 checks the sensor with the throttle almost closed: over one second the gap to manifold vacuum must shrink to near zero. GM patent US7467544 also catches a reading biased high or low. Electrical faults of such a sensor are normally stored as powertrain codes P0556 to P0559 rather than as a chassis code.
- What you may notice
- Warning lamp or message about brake assistance
- Cylinder deactivation or engine stop-start inhibited on affected vehicles
- Likely causes
- PossibleOpen or shorted sensor supply, ground or signal wire
- PossibleFaulty or drifting vacuum sensor
- RareLeaking vacuum hose, check valve or booster diaphragm
- Repair
- Medium · Often possible to do yourself.Typical cost: €30 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.