• Code: C225A
• Description: Developing motor turning at abnormal timing (K) The motor lock signal remains LOW for a predetermined continuous period of time while the motor remains stationary.
• Causes: • Developing motor (M3) • MFP board (MFPB)
• Remedy: 1. Check the connector between M3-MFPB CN4E for proper connection and correct as necessary. 2. Check the connector of M3 for proper drive coupling and correct as necessary. 3. M3 operation check • Control signal: MFPB CN4E-4 to 7 • Location of electrical component: 25-C 4. Replace M3. 5. MFPB F7E conduction check 6. Replace MFPB.

• Code: C2350
• Description: Toner suction fan motor malfunction The fan lock signal remains HIGH for a predetermined continuous period of time while the fan is turning.
• Causes: • Toner suction fan motor (FM3) • MFP board (MFPB)
• Remedy: 1. Check the connectors between FM3-relay CN301-MFPB CN12E for proper connection, and correct as necessary. 2. Check the fan for possible overload and correct as necessary. 3. FM3 operation check • Control signal: MFPB CN12E-6 (LOCK) • Location of electrical component: 26-C 4. Replace FM3. (bizhub C3851/C3351 / bizhub C3851FS) 5. MFPB F2E conduction check 6. Replace MFPB.

• Code: C2411 ... C2414
• Description: • C2411: Imaging unit/C new article release • C2412: Imaging unit/M new article release • C2413: Imaging unit/Y new article release • C2414: Imaging unit/K new article release. The status with the new unit is not cleared after the new imaging unit is set.
• Causes: • Imaging unit/Y,M,C,K • MFP board (MFPB)
• Remedy: 1. Reinstall imaging unit. 1. Check the connector between imaging unit-MFPB CN19E, CN20E for proper connection and correct as necessary. 1. Replace the imaging unit. 1. Replace MFPB.

• Code: C2551, C2553
• Description: • C2551: Abnormally low toner density detected cyan TCR sensor • C2553: Abnormally low toner density detected magenta TCR sensor When sampling data is determined in TC ratio calculation control, TCR sensor output is lower than a predetermined value for a predetermined number of times in a row even though there is toner in the toner cartridge.
• Causes: • Imaging unit/Y,M,C,K • Toner supply motor/YM (M5) • Toner supply motor/CK (M6) • MFP board (MFPB)
• Remedy: 1. Perform image troubleshooting procedure if image density is low. 2. Reinstall the imaging unit. 3. Check the connector between imaging unit-MFPB CN19E, CN20E for proper connection and correct as necessary. 4. Check the connector between M5-MFPB CN8E for proper connection and correct as necessary. 5. Check the connector between M6-MFPB CN8E for proper connection and correct as necessary. 6. M5, M6 operation check • Control signal: MFPB CN8E-1 to 4 (M5), MFPB CN8E-5 to 8 (M6) • Location of electrical component: 23-C 7. Replace the imaging unit. 8. MFPB F5E conduction check 9. Replace MFPB.

• Code: C2552, C2554
• Description: • C2552: Abnormally high toner density detected cyan TCR sensor • C2554: Abnormally high toner density detected magenta TCR sensor TC ratio in the imaging unit, which is determined by toner replenishing amount control mechanism, is a predetermined value or more for a given number of times consecutively.
• Causes: • Imaging unit/Y,M,C,K • MFP board (MFPB)
• Remedy: 1. Reinstall imaging unit. 2. Check the connector between imaging unit-MFPB CN19E, CN20E for proper connection and correct as necessary. 3. Replace the imaging unit. 4. Replace MFPB.

• Code: C2555, C2557
• Description: • C2555: Abnormally low toner density detected yellow TCR sensor • C2557: Abnormally low toner density detected black TCR sensor When sampling data is determined in TC ratio calculation control, TCR sensor output is lower than a predetermined value for a predetermined number of times in a row even though there is toner in the toner cartridge.
• Causes: • Imaging unit/Y,M,C,K • Toner supply motor/YM (M5) • Toner supply motor/CK (M6) • MFP board (MFPB)
• Remedy: 1. Perform image troubleshooting procedure if image density is low. 2. Reinstall the imaging unit. 3. Check the connector between imaging unit-MFPB CN19E, CN20E for proper connection and correct as necessary. 4. Check the connector between M5-MFPB CN8E for proper connection and correct as necessary. 5. Check the connector between M6-MFPB CN8E for proper connection and correct as necessary. 6. M5, M6 operation check • Control signal: MFPB CN8E-1 to 4 (M5), MFPB CN8E-5 to 8 (M6) • Location of electrical component: 23-C 7. Replace the imaging unit. 8. MFPB F5E conduction check 9. Replace MFPB.

• Code: C2556, C2558
• Description: • C2556: Abnormally high toner density detected yellow TCR sensor • C2558: Abnormally high toner density detected black TCR sensor TC ratio in the imaging unit, which is determined by toner replenishing amount control mechanism, is a predetermined value or more for a given number of times consecutively.
• Causes: • Imaging unit/Y,M,C,K • MFP board (MFPB)
• Remedy: 1. Reinstall imaging unit. 2. Check the connector between imaging unit-MFPB CN19E, CN20E for proper connection and correct as necessary. 3. Replace the imaging unit. 4. Replace MFPB.

• Code: C2559, C255A, C255B, C255C
• Description: • C2559: Cyan TCR sensor adjustment failure • C255A: Magenta TCR sensor adjustment failure • C255B: Yellow TCR sensor adjustment failure • C255C: Black TCR sensor adjustment failure TCR sensor automatic adjustment does not function properly, failing to adjust to an appropriate value.
• Causes: • Imaging unit/Y,M,C,K • MFP board (MFPB)
• Remedy: 1. Reinstall imaging unit. 2. Check the connector between imaging unit-MFPB CN19E, CN20E for proper connection and correct as necessary. 3. Replace the imaging unit. 4. Replace MFPB.