Chassis, generic

C0653 Left Front Wheel Speed Sensor B Circuit Low

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

C0653 means the circuit of left front sensor B sits below its valid level. Active wheel speed sensors usually signal through current steps; Allegro gives 7 and 14 mA as typical levels and a safe state below about 3.9 mA that a sensor uses to report its own fault. A reading under the lower band can therefore come from a shorted or chafed line, a supply that has dropped, or the sensor itself flagging an error. In Bosch's shared-sensor design each ECU feeds its sensors and checks supply voltage and the lines for shorts and opens. Bosch also offers a redundant-signal version of its wheel speed sensor, so the second channel is always ready for the backup actuator. No carmaker documents C0653.

Likely causes

Sensor B line chafed through and shorted to ground
Supply from the secondary control unit too low
Sensor in its fault (safe) state after an internal error

Symptoms

  • Warning for brake or driver assistance system
  • Redundant braking or automated driving not available

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€60–500
Time0.5–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

lf wss bsensor wiring

Related codes

C0651C0652C0654C0655C0502C065A

References: allegromicro.com, patents.google.com, bosch-mobility.com.