• Code: 500
• Description: Main motor lock error
  Failed to detect main motor lock signal for 7 checks in succession (total of 700ms) after main motor started to rotate, or after last lock signal was detected.
• Causes: • Main motor defective • Too much load on the drive mechanism • Motor driver damaged

• Code: 541
• Description: Fusing thermistor open
  Thermistor generated abnormal values immediately after 24V power on.
• Causes: • Fusing thermistor defective or disconnected • Fusing lamp defective • Fuse blown • PSU defective • Bad connection between fuser and machine

• Code: 542
• Description: Fusing temperature warm-up error
  During fusing warm-up, fusing temperature failed to reach target range within 22 seconds (when starting at least 25°C below the target temperature).
• Causes: • Fusing thermistor defective • Fusing lamp defective • Thermofuse blown • PSU defective • Bad connection between fuser and machine

• Code: 543
• Description: Fusing overheat error
  Detected fusing temperature remained above 230°C for 1 second.
• Causes: • Fusing thermistor defective • PSU defective

• Code: 544
• Description: Fusing low temperature error
  Detected fusing temperature remained abnormally low for 1 second during fusing operation (below 140°C) or during standby mode.
• Causes: • Fusing thermistor defective • PSU defective • Bad connection between fuser and machine

• Code: 546
• Description: Unstable fusing temperatureDetected that fusing temperature changed more than +-25°C/second two seconds in succession.
• Causes: • Fusing thermistor defective • PSU defective • Bad connection between fuser and machine

• Code: 547
• Description: Zero-cross detection error
  Detection error (detection overflow or busy) occurred 8 times in succession (at 20-ms intervals) while 24V power was on.
• Causes: • PSU defective • FCU defective

• Code: 548
• Description: Fusing-temperature range violation (too high)
  During paper transport, fusing temperature moved above limit (200°C for plain paper, 210°C for thick paper) and remained above limit for 10 seconds.
• Causes: • TRIAC short • Fan not running