ABS 5.7

Fault code 4266

Return pump fault
Return pump voltage and motor relay voltage actual values are evaluated and display implausible values

Diagnostic conditions
- Vehicle speed > 6 km/h (3.75 mph)

Possible cause of fault
- Short circuit or open circuit in the positive/ground supply to the hydraulic power unit
- Return pump motor locked up/runs too easily
- Hydraulic power unit faulty

Affected pins
Pin 1 and pin 2

Diagnosis/troubleshooting