System Error: System Error 124x: Ink Supply Sensor Error Problem Description: The Ink Supply Sensor does not change even though the specified time has passed after driving the Ink Supply Motor for the Sub-Tank. x = 0: Printhead Number 1 (Black). x = 1: Printhead Number 2 (Light Magenta). x = 2: Printhead Number 3 (Light Cyan). x = 3: Printhead Number 4 (Yellow). x = 4: Printhead Number 5 (Magenta). x = 5: Printhead Number 6 (Cyan).