• Code: 6030
• Description: Broken fuser thermistor wire
  Input from fuser thermistor is 0 (A/D value).
• Causes: Defective harness between fuser thermistor and paper exit PWB (YC4), or improper connector insertion. Defective harness between paper exit PWB (YC1) and engine PWB (YC20), or improper connector insertion. Broken fuser thermistor wire. Fuser thermistor installed incorrectly. Fuser thermal cutout triggered. Fuser heater lamp installed incorrectly. Broken fuser heater lamp wire. Defective engine PWB.
• Remedy: Defective harness between fuser thermistor and paper exit PWB (YC4), or improper connector insertion. Reinsert the connector. Also check for continuity within the connector harness. If none, remedy or replace the harness.
  Defective harness between paper exit PWB (YC1) and engine PWB (YC20), or improper connector insertion. Reinsert the connector. Also check for continuity within the connector harness. If none, remedy or replace the harness.
  Broken fuser thermistor wire. Replace the fuser unit.
  Fuser thermistor installed incorrectly. Replace the fuser unit.
  Fuser thermal cutout triggered. Replace the fuser unit.
  Fuser heater lamp installed incorrectly. Replace the fuser unit.
  Broken fuser heater lamp wire. Replace the fuser unit.
  Defective engine PWB. Replace the engine PWB.

• Code: 6400
• Description: Zero cross signal error
  The zero cross signal does not reach the engine PWB for specified time.
• Causes: Defective harness between power source PWB (YC103) and engine PWB (YC19), or improper connector insertion. Defective power source PWB. Defective engine PWB.
• Remedy: Defective harness between power source PWB (YC103) and engine PWB (YC19), or improper connector insertion. Reinsert the connector. Also check for continuity within the connector harness. If none, remedy or replace the harness.
  Defective power source PWB. Replace the power source PWB.
  Defective engine PWB. Replace the engine PWB.

• Code: 7001
• Description: Toner motor K error
  Over-current at toner motor K is detected for 80 ms in total while toner motor K is ON.
• Causes: Defective harness between toner motor K and engine PWB (YC22), or improper connector insertion. Defective drive transmission system of the toner motor K. Defective toner motor K. Defective engine PWB.
• Remedy: Defective harness between toner motor K and engine PWB (YC22), or improper connector insertion. Reinsert the connector. Also check for continuity within the connector harness. If none, remedy or replace the harness.
  Defective drive transmission system of the toner motor K. Check if the gears rotate smoothly. If not, grease the bushings and gears. Check for broken gears and replace if any.
  Defective toner motor K. Replace the toner motor K.
  Defective engine PWB. Replace the engine PWB.

• Code: 7002
• Description: Toner motor C error
  Over-current at toner motor C is detected for 80 ms in total while toner motor C is ON.
• Causes: Defective harness between toner motor C and engine PWB (YC24), or improper connector insertion. Defective drive transmission system of the toner motor C. Defective toner motor C. Defective engine PWB.
• Remedy: Defective harness between toner motor C and engine PWB (YC24), or improper connector insertion. Reinsert the connector. Also check for continuity within the connector harness. If none, remedy or replace the harness.
  Defective drive transmission system of the toner motor C. Check if the gears rotate smoothly. If not, grease the bushings and gears. Check for broken gears and replace if any.
  Defective toner motor C. Replace the toner motor C.
  Defective engine PWB. Replace the engine PWB.

• Code: 7003
• Description: Toner motor M error
  Over-current at toner motor M is detected for 80 ms in total while toner motor M is ON.
• Causes: Defective harness between toner motor M and engine PWB (YC25), or improper connector insertion. Defective drive transmission system of the toner motor M. Defective toner motor M. Defective engine PWB.
• Remedy: Defective harness between toner motor M and engine PWB (YC25), or improper connector insertion. Reinsert the connector. Also check for continuity within the connector harness. If none, remedy or replace the harness.
  Defective drive transmission system of the toner motor M. Check if the gears rotate smoothly. If not, grease the bushings and gears. Check for broken gears and replace if any.
  Defective toner motor M. Replace the toner motor M.
  Defective engine PWB. Replace the engine PWB.

• Code: 7004
• Description: Toner motor Y error
  Over-current at toner motor Y is detected for 80 ms in total while toner motor Y is ON.
• Causes: Defective harness between toner motor Y and engine PWB (YC23), or improper connector insertion. Defective drive transmission system of the toner motor Y. Defective toner motor Y. Defective engine PWB.
• Remedy: Defective harness between toner motor Y and engine PWB (YC23), or improper connector insertion. Reinsert the connector. Also check for continuity within the connector harness. If none, remedy or replace the harness.
  Defective drive transmission system of the toner motor Y. Check if the gears rotate smoothly. If not, grease the bushings and gears. Check for broken gears and replace if any.
  Defective toner motor Y. Replace the toner motor Y.
  Defective engine PWB. Replace the engine PWB.

• Code: 7401
• Description: Developing unit K non-installing error
  No density detection signal is output from toner sensor K in developing unit K.
• Causes: Defective harness between developing unit K and drum relay PWB (YC4), or improper connector insertion. Defective harness between drum relay PWB (YC1) and engine PWB (YC34), or improper connector insertion. Defective toner sensor K. Defective engine PWB.
• Remedy: Defective harness between developing unit K and drum relay PWB (YC4), or improper connector insertion. Reinsert the connector. Also check for continuity within the connector harness. If none, remedy or replace the harness.
  Defective harness between drum relay PWB (YC1) and engine PWB (YC34), or improper connector insertion. Reinsert the connector. Also check for continuity within the connector harness. If none, remedy or replace the harness.
  Defective toner sensor K. Replace the developing unit K.
  Defective engine PWB. Replace the engine PWB.

• Code: 7402
• Description: Developing unit C non-installing error
  No density detection signal is output from toner sensor C in developing unit C.
• Causes: Defective harness between developing unit C and drum relay PWB (YC10), or improper connector insertion. Defective harness between drum relay PWB (YC1) and engine PWB (YC34), or improper connector insertion. Defective toner sensor C. Defective engine PWB.
• Remedy: Defective harness between developing unit C and drum relay PWB (YC10), or improper connector insertion. Reinsert the connector. Also check for continuity within the connector harness. If none, remedy or replace the harness.
  Defective harness between drum relay PWB (YC1) and engine PWB (YC34), or improper connector insertion. Reinsert the connector. Also check for continuity within the connector harness. If none, remedy or replace the harness.
  Defective toner sensor C. Replace the developing unit C.
  Defective engine PWB. Replace the engine PWB.