Code Definition

C0031 — Left Front Wheel Speed Sensor Circuit

System: Chassis  |  Type: Generic (OBD-II Standard)  |  Make: Generic

About C0031

C0031 is a generic (obd-ii standard) chassis diagnostic trouble code. It belongs to the C-prefix family of codes, which covers chassis, braking, steering, suspension, or stability-control faults.

When C0031 is stored, the module has detected a sensor-related fault — the reported value from the named sensor is out of spec.

Scanning & clearing: Chassis (C) codes are stored in the ABS, traction control, or stability-control modules. An enhanced or OEM-level scan tool is usually required to read and clear them.

Because C0031 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

The Antilock Brake System (ABS) control module continuously monitors the left front wheel speed sensor circuit for a valid alternating or digital signal that corresponds to wheel rotation. Most modern systems use a hall effect (active) sensor that outputs a digital square wave proportional to wheel speed and draws a current pattern the ABS module can monitor, while older systems use a passive variable reluctance (AC) sensor whose output amplitude rises with wheel speed. DTC C0031 is set when the ABS module detects an electrical fault on the left front wheel speed sensor circuit such as an open...

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