• Code: C2556, C2558
• Description: • C2556: Abnormally high toner density detected yellow TCR sensor • C2558: Abnormally high toner density detected black TCR sensor. The TC ratio of the toner determined by the toner replenishment control is detected to be the predetermined value or over for consecutive times.
• Causes: • Developing unit/C,M,Y,K • Toner cartridge/C,M,Y,K • Front side board (FRB) • MFP board (MFPB)
• Remedy: 1. Reinstall developing unit. 2. Reinstall toner cartridge. 3. Check the connector between the developing unit-FRB CN13 (C2558), CN14 (C2552), CN15 (C2554), CN16 (C2556) for proper connection and correct as necessary. 4. Check the connector between FRB CN1, CN3-MFPB CN4E, CN11E for proper connection and correct as necessary. 5. Replace the developing unit. 6. Replace FRB. 7. Replace MFPB.

• Code: C2557
• Description: Abnormally low toner density detected black TCR sensor. When sampling data is determined in TC ratio calculation control, TCR sensor output is higher than a predetermined value for a predetermined number of times in a row even though there is toner in the sub hopper.
• Causes: • Developing unit/K • Toner cartridge/K • Toner empty sensor/K (PS31) • Toner cartridge motor/K (M25) • Toner supply motor/K (M6) • Front side board (FRB) • MFP board (MFPB)
• Remedy: 1. Perform image troubleshooting procedure if image density is low. 2. Reinstall developing unit/K. 3. Reinstall toner cartridge/K. 4. Check the connector between the developing unit/K-FRB CN13 for proper connection and correct as necessary. 5. Check the connector between FRB CN1, CN3-MFPB CN4E, CN11E for proper connection and correct as necessary. 6. M25 operation check • Control signal: MFPB CN30E-1 to 4 • Location of electrical component: 16-C 7. M6 operation check • Control signal: MFPB CN30E-5 to 8 • Location of electrical component: 17-C 8. If the toner empty sensor and its surroundings inside the sub hopper are dirtied with toner, clean them. 9. Replace the developing unit/K. 10. Replace FRB. 11. Replace MFPB.

• Code: C2559, C255A, C255B
• Description: • C2559: Cyan TCR sensor adjustment failure • C255A: Magenta TCR sensor adjustment failure • C255B: Yellow TCR sensor adjustment failure. TCR sensor automatic adjustment does not function properly, failing to adjust to an appropriate value.
• Causes: • Developing unit/C,M,Y • Toner cartridge motor/Y,M,C (M10) • Toner supply motor/Y (M9) • Toner supply motor/M (M8) • Toner supply motor/C (M7) • Front side board (FRB) • MFP board (MFPB)
• Remedy: 1. Reinstall developing unit. 2. Check the connector between the developing unit-FRB CN14 (C2559), CN15 (C255A), CN16 (C255B) for proper connection and correct as necessary. 3. Check the connector between FRB CN1, CN3-MFPB CN4E, CN11E for proper connection and correct as necessary. 4. M10 operation check • Control signal: MFPB CN16E-1 to 4 • Location of electrical component: 15-C 5. M7, M8, M9 operation check • Control signal: MFPB CN16E-5 to 8 (M7), MFPB CN16E-9 to 12 (M8), MFPB CN16E-13 to 16 (M9) • Location of electrical component: 15-C (M7, M8), 16-C (M9) 6. Replace the developing unit. 7. Replace FRB. 8. Replace MFPB.

• Code: C255C
• Description: Black TCR sensor adjustment failure. TCR sensor automatic adjustment does not function properly, failing to adjust to an appropriate value.
• Causes: • Developing unit/K • Toner cartridge motor/K (M25) • Toner supply motor/K (M6) • Front side board (FRB) • MFP board (MFPB)
• Remedy: 1. Reinstall developing unit/K. 2. Check the connector between the developing unit/K-FRB CN13 for proper connection and correct as necessary. 3. Check the connector between FRB CN1, CN3-MFPB CN4E, CN11E for proper connection and correct as necessary. 4. M25 operation check • Control signal: MFPB CN30E-1 to 4 • Location of electrical component: 16-C 5. M6 operation check • Control signal: MFPB CN30E-5 to 8 • Location of electrical component: 17-C 6. Replace the developing unit/K. 7. Replace FRB. 8. Replace MFPB.

• Code: C2561, C2562
• Description: • C2561: Cyan TCR sensor failure • C2562: Magenta TCR sensor failure. Alarm signals for each TCR sensor is detected more than the predetermined number of times. This detection is used for detecting disconnection of TCR sensor connector.
• Causes: • Developing unit/C,M,Y,K • Front side board (FRB) • MFP board (MFPB)
• Remedy: 1. Reinstall developing unit. 2. Check the connector between the developing unit-FRB CN13 (C2564), CN14 (C2561), CN15 (C2562), CN16 (C2563) for proper connection and correct as necessary. 3. Check the connector between FRB CN1, CN3-MFPB CN4E, CN11E for proper connection and correct as necessary. 4. Replace the developing unit. 5. Replace FRB. 6. MFPB ICP2E conduction check 7. Replace MFPB.

• Code: C2563, C2564
• Description: • C2563: Yellow TCR sensor failure • C2564: Black TCR sensor failure. Alarm signals for each TCR sensor is detected more than the predetermined number of times. This detection is used for detecting disconnection of TCR sensor connector.
• Causes: • Developing unit/C,M,Y,K • Front side board (FRB) • MFP board (MFPB)
• Remedy: 1. Reinstall developing unit. 2. Check the connector between the developing unit-FRB CN13 (C2564), CN14 (C2561), CN15 (C2562), CN16 (C2563) for proper connection and correct as necessary. 3. Check the connector between FRB CN1, CN3-MFPB CN4E, CN11E for proper connection and correct as necessary. 4. Replace the developing unit. 5. Replace FRB. 6. MFPB ICP2E conduction check 7. Replace MFPB.

• Code: C2650
• Description: Main backup media access error. • The re-written data, which has been read out, checked and founded as error, is read out again and found as error. • The error was found when reading out the counter value. • The main body detects that the EEPROM is not mounted.
• Causes: • EEPROM/1 • EEPROM/2 • MFP board (MFPB)
• Remedy: 1. Make sure that EEPROM/1 and EEPROM/2 are mounted in their respective correct positions. 2. Check to see if the EEPROM is mounted in a reverse direction. 3. Check the connector from MFPB to EEPROM for proper connection and correct as necessary. 4. Replace MFPB. 5. Replace EEPROM/1 and EEPROM/2. 1. Replace the current EEPROM with a new one. 2. Replace the following components with new ones. When the transfer belt unit and the fusing unit have been replaced with new ones, perform [New Release] in the service mode. When the transfer roller has been replaced with a new one, perform [Counter clear]. • Developing unit/Y,M,C,K • Drum unit/Y,M,C,K • Toner cartridge/Y,M,C,K • Transfer belt unit • Fusing unit • Transfer roller • Feed roller, pick-up roller, separation roller (including options) 3. Turn ON the main power switch and check to see that warm-up is started. Make sure that malfunction codes other than C2650 or improper IU/TC placement is not detected. 4. Make the specified readjustments. 6. If the above actions do not solve the problem, contact KM.

• Code: C2A11, C2A12
• Description: • C2A11: Drum unit/C new release failure • C2A12: Drum unit/M new release failure. The status with the new unit is not cleared after the new drum unit is set.
• Causes: • Drum unit/C,M,Y,K • Front side board (FRB) • MFP board (MFPB)
• Remedy: 1. Clean the connection between the drum unit and the machine if dirty. 2. Reinstall the drum unit. 3. Check the connector between the drum unit-FRB CN12 for proper connection and correct as necessary. 4. Check the connector between FRB CN1, CN3-MFPB CN4E, CN11E for proper connection and correct as necessary. 5. Replace the drum unit. 6. Replace FRB. 7. Replace MFPB.