C0651Left Front Wheel Speed Sensor B Circuit/Open
- Generic OBD-II code · Chassis
- Can trigger limp mode
- How the car detects it
- C0651 reports an open circuit at the second speed sensor of the left front wheel. Sensor B exists only where a wheel carries two independent speed signals, mainly in redundant brake systems for automated driving. Continental describes two layouts: two separate sensors per wheel, each wired to its own brake control unit, or one housing with two sensing elements, each with its own two-wire cable that can run to a different controller. On such two-wire sensors the signal rides on the supply current, and Allegro notes that the module can spot opens and shorts simply from the current drawn. No carmaker publishes C0651. Sensor A (C0500) usually keeps ABS working, but the redundancy is lost.
- What you may notice
- Warning for brake or driver assistance system
- Automated driving or redundant brake functions unavailable
- Likely causes
- LikelyBroken wire in the sensor B cable near the wheel
- PossiblePlug of the second channel loose or corroded
- RareSecond sensing element inside the sensor failed open
- Repair
- Medium · Usually a job for a workshop.Typical cost: €60 – €500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.