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C1123 Manufacturer-specific Basic entry

Vehicle Speed Sensor Input Short to Battery

Updated 2026-10-02 · Chassis (manufacturer-specific)

Severity
Medium
Typical repair cost
40 – 350 EUR
System
Chassis

This is a manufacturer-specific code. Its exact meaning can differ between makes; the definition below follows the most common usage.

What it means

C1123 is stored when the chassis control module (ABS/ESP) measures a voltage in the Vehicle Speed Sensor Input circuit above the expected maximum, typically because the signal wire is shorted to battery voltage or the circuit is open and pulled up internally.

This entry is compiled automatically from the standard definition and typical diagnostic practice for this type of fault. A detailed, reviewed article is in preparation.

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Symptoms

  • ABS, ESP or traction control warning light
  • Stability and traction systems disabled
  • Possible longer braking distance in emergency stops
  • Speedometer or cruise control affected in some vehicles

Common causes

  1. Damaged, chafed or corroded wiring in the Vehicle Speed Sensor Input circuit
  2. Corroded, loose or water-damaged connector terminals
  3. Failed Vehicle Speed Sensor Input component (sensor, solenoid or actuator)
  4. Poor ground connection for the module or component
  5. Faulty control module driver (rare, confirm all else first)

How to diagnose

  1. Read freeze frame data and note when the code set (cold start, under load, after rain)
  2. Inspect the Vehicle Speed Sensor Input connector for bent pins, corrosion and water; wiggle the harness with the engine running and watch live data
  3. Measure supply voltage and ground at the connector with the key on
  4. Check the signal wire for shorts to ground or battery and for continuity to the control module
  5. Test or substitute the Vehicle Speed Sensor Input only after wiring and connectors are confirmed good
  6. Clear the code and complete a drive cycle to confirm the repair

Frequently asked questions

Can I keep driving with C1123?

Usually yes for a short time, but expect reduced performance or higher fuel use. Have it diagnosed within a few days.

Will clearing C1123 fix it?

No. Clearing only erases the stored code; it returns as soon as the monitor runs again unless the cause is repaired.

Related codes

C1124C1125

Nearby codes in this group