Fault code C1161 – a step-by-step guide to diagnosing and fixing it

Error code C1161 is displayed and the check engine light is on - what does this mean?

The DTC C1161 is recognized by the OBD/EOBD system and indicates a defect in the ABS system, or more precisely, low system pressure in the brake hydraulics. This trouble code mainly affects the hydraulic pump and the pressure sensor of the anti-lock braking system. For various manufacturers, this error code can also be referred to as "ABS Hydraulic Pump Motor Circuit Low".

What causes can this fault code have?

• Defective ABS hydraulic pump
• Damaged brake pressure sensor
• Loose or corroded plug connections in the ABS system
• Defective fuse in the ABS pump
• Low brake fluid in the system
• Blocked brake fluid lines
• Defective ABS control unit
• Damaged wiring harness to the hydraulic pump
• Internal leak in the ABS hydraulic block

What symptoms occur in parallel with fault code C1161?

• ABS warning light illuminates: The anti-lock braking system is deactivated
• Hard brake pedal operation: Increased effort required when braking
• Increased braking distances: The vehicle requires more distance to stop
• Pumping noises: Unusual noises from the engine compartment when braking
• Grinding brake noises: Metallic noises during the braking process
• Vibrations in the brake pedal: Noticeable vibrations when the brake is applied

How can the problem with fault code C1161 be rectified?

• Repairing fault code C1161 requires a systematic approach to identify the cause.
• Check and top up the brake fluid level: Check the level in the brake fluid reservoir and top up with the manufacturer's recommended brake fluid if necessary, then bleed the system
• Replace ABS fuses: Check all fuses in the ABS system and replace defective fuses with new ones of the correct amperage
• Clean and tighten plug connections: Disconnect all electrical connections to the ABS pump, clean the contacts with contact spray and re-establish firm connections
• Replace brake pressure sensor: Remove the defective pressure sensor from the ABS hydraulic block and install a new sensor with the correct torques
• Replace ABS hydraulic pump: Remove the complete hydraulic pump, install a new or reconditioned pump and perform a complete system flush
• Program the ABS control unit: Have the ABS module reprogrammed or replaced by a specialist workshop with the appropriate diagnostic technology