Fault code C1172 – a step-by-step guide to diagnosing and fixing it

Error code C1172 is displayed and the check engine light is on - what does this mean?

The DTC C1172 is recognized by the OBD/EOBD system and indicates a problem with the ABS sensor or the anti-lock braking system. This fault code mainly affects the wheel speed sensors and the associated circuits. The exact designation may vary for different manufacturers, but generally refers to faults in the ABS system.

What causes can this fault code have?

• Defective ABS wheel speed sensor
• Damaged or corroded sensor cable
• Loose or dirty plug connections
• Defective sensor ring on the wheel
• Faulty ABS control unit
• Interruption in the wiring
• Contamination or damage to the sensor area
• Defective ground or power supply

What symptoms occur in parallel with fault code C1172?

• ABS warning light: The ABS indicator light in the dashboard lights up continuously
• Check engine light: The check engine light can also be activated
• Locking wheels: The anti-lock braking system is no longer working properly
• ESP malfunction: Electronic stability programs may be impaired
• Braking behavior: Changed braking characteristics, especially during emergency braking
• Vehicle diagnostics: OBD scanner displays the specific trouble code C1172

How can the problem with error code C1172 be rectified?

• Repairing trouble code C1172 requires a systematic approach to identifying and eliminating the cause.
• Replace the ABS sensor: Locate the defective wheel speed sensor and replace it with a new original part, taking note of the correct mounting position and air gap
• Repair wiring: Identify damaged cables between sensor and control unit, repair severed or corroded areas or replace the complete wiring harness
• Clean plug connections: Clean all electrical connections on the ABS system, treat contacts with contact spray and screw tightly
• Replace the sensor ring: Check the pulse ring on the affected wheel for damage and replace if there are cracks or missing teeth
• Replace the ABS control unit: If the control unit is defective, have the complete ABS module replaced with a programmed spare part
• Perform a system reset: After the repair, delete the fault code with an OBD scanner and carry out a test drive to check the function