This code indicates that the left front wheel speed sensor "B" signal is operating outside its expected range or performing erratically, as detected by the ABS or stability control module. Unlike a total circuit failure, the sensor is producing a signal, but its amplitude, frequency, or pattern is inconsistent with other wheels or internal thresholds. This typically affects antilock braking, traction control, and stability systems.
Internal degradation of the sensor’s coil or Hall-effect element can produce a weak, noisy, or irregular signal that falls outside the module’s acceptable range.
Frayed, chafed, or moisture-corroded wiring and pins in the wheel-well harness can create intermittent opens, shorts, or high resistance that distorts sensor output.
A cracked, loose, or rust-covered reluctor ring alters the magnetic or optical pattern seen by the sensor, causing erratic pulse trains interpreted as a performance fault.
Physical damage, worn mounting bosses, or improper installation can increase the gap between the sensor and tone ring beyond specification, weakening the signal.
In rare cases, an internal fault in the antilock brake module may misinterpret a valid sensor signal; this should only be considered after sensor, wiring, and tone ring integrity are verified.
Normal hydraulic braking usually remains, but ABS, traction control, and stability control may be disabled. Drive cautiously and repair promptly to restore safety systems.
It means the sensor circuit is electrically intact, but the signal strength, frequency, or pattern is outside expected limits—often from a weak sensor, debris, or tone-ring damage rather than a complete open or short.
No. This code is almost always caused by the wheel speed sensor, its wiring, or the tone ring. Replacing the PCM—or even the ABS/EBCM—is usually unnecessary and should only be considered after all sensor and circuit tests prove normal.
The "B" designation identifies a specific circuit or secondary sensor at the left front wheel on vehicles with redundant or multi-channel wheel speed monitoring architectures.