C0661Left Rear Wheel Speed Sensor B Circuit Low
- Generic OBD-II code · Chassis
- Can trigger limp mode
- How the car detects it
- With C0661 the second left rear speed signal sits below the lowest level an intact sensor ever outputs, typically because the signal lead touches ground or the sensor feed has collapsed. No carmaker documents this code. What normal looks like is shown by a Motor magazine measurement on Honda sensors: a healthy unit switches cleanly between about 0.70 V and 1.40 V with a 50 % duty cycle, and a pickup magnet held against the sensor tip makes it switch. A level that stays below the lower band therefore points to wiring rather than to the encoder. Rear wheel speeds matter beyond ABS: in an HL Mando design the electric parking brake on the rear wheels uses them to calculate slip and backs off before a wheel locks during an emergency stop.
- What you may notice
- Warning for brake or stability system shortly after start
- Emergency braking support of the electric parking brake may be restricted
- Likely causes
- LikelySignal lead chafed through and touching ground
- PossibleSensor supply pulled down, e.g. by water in the plug
- RareSensor B shorted internally
- Repair
- Medium · Usually a job for a workshop.Typical cost: €60 – €450
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.