Code Definition

C1123 — Vehicle Speed Sensor Input Short to Battery

System: Chassis  |  Type: Manufacturer-Specific  |  Make: Generic

About C1123

C1123 is a manufacturer-specific chassis diagnostic trouble code. It belongs to the C-prefix family of codes, which covers chassis, braking, steering, suspension, or stability-control faults.

When C1123 is stored, the module has detected a short-circuit (voltage pulled to ground or to supply) in the monitored circuit; and 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.

C1123 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

This code relates to the vehicle speed sensor (VSS) signal that the chassis control module, typically the ABS or electronic brake control module, monitors to determine road speed. C1123 sets when the module detects that the VSS input circuit is shorted to battery voltage, causing the signal to read abnormally high or stay fixed regardless of actual wheel or output shaft rotation. The speed signal may originate from a wheel speed sensor, a transmission output speed sensor, or be distributed on the data network, and the module uses it for ABS, traction control, and speed dependent functions. Whe...

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