C1241: Definitions depend on the manufacturer — what it means, the affected system and what to check before replacing parts.
Meaning, symptoms, causes and checks
ABS Hydraulic Pressure Differential Switch Input Short Circuit To Ground. Source catalogue definition; confirm applicability using vehicle service information.
Affected system: Chassis
Symptoms
- Illuminated ABS warning light
- Illuminated brake system warning light
- Loss of anti-lock braking system function
- Reduced braking stability during emergency stops
- Possible traction control system malfunction
Possible causes
- Short circuit to ground in the pressure switch wiring harness
- Damaged or chafed wiring insulation
- Internal failure of the hydraulic pressure differential switch
- Corroded or damaged electrical connector pins
- Water ingress into the switch connector
What to check
- Inspect the wiring harness for signs of physical damage or rubbing against the chassis
- Measure voltage at the pressure switch connector to identify short-to-ground conditions
- Clean the electrical connectors with contact cleaner and check for oxidation
- Test the continuity of the signal circuit back to the ABS control module
- Verify the output signal of the hydraulic pressure switch using a multimeter
Also written as: C1241-00, C124100 (some scan tools add the fault-type byte, e.g. -00).