Error Code C2154 is a Rank B imaging engine fault generated when the machine detects that the 1st transfer pressure sensor (PS39) does not detect a switch from the retraction position to the pressure position within the allowed time after the 1st transfer pressure clutch (CL5) has started engagement. In plain terms: the machine commanded the intermediate transfer belt (ITB) to make contact with all four photoconductor drums — the “all pressure” state required for full-colour printing — but received no confirmation from PS39 that the belt mechanism actually reached the contact position.
C2154 belongs to a tightly related group of transfer belt pressure codes (C2152 through C2156) that all involve the same three components — PS39, CL5, and the fusing motor M3 — but detect different failure conditions at different points in the pressure/retraction cycle. C2154 is specifically the code for a contact failure (retraction-to-pressure direction) during the all-colour pressure switching sequence, as distinct from C2153 (retraction failure at K pressure switching) or C2155 (contact failure after K pressure is already established).
This code is a Rank B fault, meaning the machine halts all printing and the error must be addressed by a technician. Because the transfer belt pressure mechanism is driven by the same fusing motor (M3) that drives the fuser, and because it uses the same clutch-and-cam architecture, C2154 is one of the more mechanically involved error codes in the C225x–C225x generation of bizhub colour machines. However, the most common root cause in the field — a loose connector at PS39 or CL5 — takes minutes to check and resolves the majority of C2154 calls before any components are replaced.
| Field | Details |
|---|---|
| Error Code | C2154 |
| Description | Transfer belt contact fault at all pressure switching |
| Error Rank | B — machine halts all printing; requires technician intervention to resolve |
| Detection Condition | The 1st transfer pressure sensor (PS39) does not detect the switch from retraction to pressure (does not turn ON/blocked) within the allowed time after the 1st transfer pressure clutch (CL5) has started engagement during the all-colour pressure sequence |
| Key Components | Fusing motor (M3), 1st transfer pressure clutch (CL5), 1st transfer pressure sensor (PS39), control board (MFPB, EXCB, BASEB — varies by model; see table) |
| PS39 Signal — C258/C308/C368 | MFPB CN15EB-17 (ON); location: 10-C |
| CL5 Signal — C258/C308/C368 | MFPB CN15EA-18 (ON); location: 8-C |
| M3 Signal — C258/C308/C368 | MFPB CN8E-9 (REM), MFPB CN8E-12 (LOCK); location: 2-C |
| PS39 Signal — C458/C558/C658 | MFPB CN15E (I/O); location: 10-C; CL5 via EXCB CN8 |
| PS39 Signal — C227/C287 | MFPB CN7E<B>-13 (ON); location: 22-C |
| CL5 Signal — C227/C287 | MFPB CN12E-12 (ON); location: 5-C |
| M3 Signal — C227/C287 | MFPB CN11E-11 (REM), MFPB CN11E-14 (FGP); location: 3-C |
| PS39 Signal — C750i | BASEB CN13E (I/O); CL5 via EXCB CN14EX; location: refer to wiring diagram |
| MFPB Fuse — C458/C258/C308/C368 | MFPB ICP2E (C458) — conduction check required before board replacement |
| MFPB Fuse — C227/C287 | MFPB F13E — conduction check required before board replacement |
| Related Codes | C2152 (transfer belt fault at initial position return), C2153 (transfer belt spacing fault at K pressure switching), C2155 (transfer belt contact fault after K pressure established), C2156 (transfer belt spacing fault after all pressure established) |
All Affected Models
C2154 applies to the main range of bizhub colour models using the PS39 / CL5 / M3 transfer belt pressure architecture. The connector paths for PS39 and CL5 differ between model families — confirming the correct model group is essential before beginning any connector check. The control board architecture also differs for higher-end platforms (EXCB and BASEB are introduced on the larger models).
| bizhub Models | PS39 Connector Path | PS39 I/O Signal | CL5 Connector Path | M3 Connector | Board(s) Involved | MFPB Fuse |
|---|---|---|---|---|---|---|
| bizhub C227 / C287 | PS39 — relay CN24 — MFPB CN7E | MFPB CN7E<B>-13 (ON); 22-C | CL5 — relay CN29 — MFPB CN12E | M3 — MFPB CN11E; CN11E-11 (REM), CN11E-14 (FGP); 3-C | MFPB | MFPB F13E |
| bizhub C258 / C308 / C368 | PS39 — relay CN113 — MFPB CN15EB | MFPB CN15EB-17 (ON); 10-C | CL5 — relay CN118 — MFPB CN15EA | M3 — MFPB CN8E; CN8E-9 (REM), CN8E-12 (LOCK); 2-C | MFPB | MFPB ICP2E |
| bizhub C458 / C558 / C658 | PS39 — relay CN113 — MFPB CN15E | MFPB CN15EB-17 (ON); 10-C | CL5 — relay CN118 — EXCB CN8 | M3 — MFPB CN8E; CN8E-9 (REM), CN8E-12 (LOCK); 2-C | MFPB + EXCB | MFPB ICP2E |
| bizhub C450i / C550i / C650i | PS39 — relay CN113 — MFPB CN15E | MFPB CN15E (I/O) | CL5 — relay CN118 — EXCB CN8 | M3 — MFPB CN8E; 2-C | MFPB + EXCB | Refer to service manual |
| bizhub C750i | PS39 — relay CN113 — BASEB CN13E | BASEB CN13E (I/O) | CL5 — relay CN118 — EXCB CN14EX | M3 — refer to service manual | BASEB + EXCB + CPUB | Refer to service manual |
| bizhub C224 / C284 / C364 | PS39 — relay CN113 — PRCB CN13 | PRCB CN13-7 (ON); 24-C | CL5 — relay CN118 — PRCB CN13 | M3 — PRCB CN2; CN2-9 (REM), CN2-12 (LOCK); 27-I to J | PRCB | Refer to service manual |
| bizhub C224e / C284e / C364e | PS39 — relay CN113 — PRCB CN13 | PRCB CN13-7 (ON); 24-C | CL5 — relay CN118 — PRCB CN13 | M3 — PRCB CN2; CN2-9 (REM), CN2-12 (LOCK); 27-I to J | PRCB | Refer to service manual |
| bizhub C454 / C554 | Refer to service manual | Refer to service manual | Refer to service manual | Refer to service manual | MFPB | Refer to service manual |
| bizhub C454e / C554e | Refer to service manual | Refer to service manual | Refer to service manual | Refer to service manual | MFPB | Refer to service manual |
ℹ️ Important note on relay connectors: Both PS39 and CL5 route through intermediate relay connectors before reaching the main control board. PS39 uses relay CN24 (C227/C287) or relay CN113 (C258 and newer models). CL5 uses relay CN29 (C227/C287) or relay CN118 (C258 and newer). On the C458/C558/C658 and C750i platform, CL5 routes through the EXCB rather than the MFPB directly. All relay connectors must be included in the connector inspection — checking only the board-end connector while leaving the relay connector unseated is a common diagnostic shortcut that leads to missed root causes.
What Does Error Code C2154 Mean?
In a colour bizhub, the intermediate transfer belt (ITB) serves as the carrier surface onto which toner images from each of the four photoconductor drums (Y, M, C, K) are transferred before the combined full-colour image is transferred to paper at the 2nd transfer point. For the toner to transfer from the photoconductor drums to the belt, the belt must be held in firm contact with each drum by the 1st transfer rollers pressing from behind the belt surface.
However, the machine does not maintain belt contact with all four drums continuously. In K-only (monochrome black) print mode, only the K drum needs to be in contact with the belt — the Y, M, and C drums are retracted to reduce wear on both the ITB and the colour drums during mono printing. When switching to full-colour mode, the machine must bring the belt from the K-only (partial contact) state into the “all pressure” state where all four drum positions are in contact with the belt. This transition is what C2154 monitors.
The mechanism that controls ITB pressure uses the fusing motor (M3) as its power source, with the 1st transfer pressure clutch (CL5) engaging to transmit M3’s rotation into a cam mechanism that physically shifts the ITB contact rollers. The 1st transfer pressure sensor PS39 is a photo-interrupter or switch that detects when the cam mechanism has reached the “all pressure” position by detecting the position of a flag or actuator driven by the cam.
C2154 fires when the sequence below fails at the detection step:
- The machine determines that all-colour printing is required.
- The MFPB (or PRCB/BASEB depending on model) commands CL5 to engage, connecting M3’s rotation to the transfer pressure cam.
- The cam begins rotating from the retraction position toward the all-pressure position.
- PS39 should detect the cam reaching the all-pressure position and turn ON (blocked) within the allowed timeout.
- If PS39 does not turn ON within the timeout, C2154 is generated.
The failure can occur at any point in the chain: M3 not running, CL5 not engaging, the cam mechanism seized or damaged, PS39 unable to detect the cam flag even though the cam reached the position, or an open circuit in any of the connector paths preventing the signal from reaching the control board.
ℹ️ C2154 vs C2155 — a critical distinction: C2154 fires during the switch to all-colour pressure (from retraction or from K-only contact to full YMCK contact). C2155 fires when contact is not confirmed after K pressure has already been established — i.e., the K pressure step succeeded but the additional YMC pressure step failed. Both codes involve PS39 and CL5, but they detect failure at different stages of the same sequence. If a machine generates both codes simultaneously, the cam mechanism itself is the most likely culprit — it failed at the first all-pressure transition, which then also prevents the secondary YMC confirmation.
The Role of M3 in the Transfer Belt Pressure System
The fusing motor M3 serves a dual purpose on this machine family: it drives the fusing roller pair to fuse toner to paper, and it provides the mechanical power for the transfer belt pressure/retraction cam mechanism via CL5. This shared drive architecture has an important diagnostic implication: if M3 itself has failed or is not running, both the fusing function and the transfer belt pressure function will be affected simultaneously. A machine that shows both a fusing fault and C2154 almost certainly has an M3 failure rather than a problem specifically with the transfer belt pressure mechanism.
Conversely, if the fusing unit is functioning correctly — sheets are being fused and the fusing roller is hot — M3 is most likely running, and C2154 should be investigated at the CL5 clutch or PS39 sensor level rather than at M3.
Common Causes of C2154
- Loose or disconnected connector in the PS39 signal path — the most common cause. PS39’s signal travels through an intermediate relay connector (CN24 on C227/C287; CN113 on C258 and later models) before reaching the main control board. A loose relay connector or a loose board-end connector on MFPB CN7E (C227/C287), MFPB CN15EB (C258/C308/C368), MFPB CN15E (C458/C558/C658), or BASEB CN13E (C750i) produces C2154 because the MFPB/BASEB receives no PS39 signal change regardless of the cam’s physical position. This is the most frequently confirmed root cause across all model generations and should always be the first point inspected.
- Loose or disconnected connector in the CL5 clutch signal path. CL5 routes through relay connector CN29 (C227/C287) or CN118 (C258 and later) before reaching MFPB CN12E (C227/C287), MFPB CN15EA (C258/C308/C368), EXCB CN8 (C458/C558/C658), or EXCB CN14EX (C750i). A loose CL5 connector means the clutch never receives its engagement command, so the cam never begins rotating from retraction and PS39 never turns ON.
- PS39 sensor contamination, misalignment, or failure. The PS39 photo-interrupter or mechanical switch accumulates toner and paper dust from the imaging area. If the sensor’s optical faces are contaminated, the cam flag cannot interrupt the beam even when the cam has physically reached the all-pressure position — the machine concludes the cam did not arrive when it actually did. Misalignment of PS39 from its mounting bracket — possible after a machine was transported, after a rear-panel reassembly, or after a rough jam clearance — produces the same effect.
- CL5 clutch failure. The 1st transfer pressure clutch is an electromagnetic clutch that engages M3’s drive to the pressure cam when energized. A failed CL5 coil, a seized CL5 mechanism, or a clutch that has worn to the point where it slips rather than positively engaging will prevent the cam from moving even when M3 is running and CL5 receives its command signal. CL5 failure is confirmed in field reports as one of the component replacements most commonly required to resolve the C215x code group.
- Transfer belt pressure cam mechanism seized or damaged. The cam that drives the ITB contact rollers between the retraction and all-pressure positions can seize due to lubrication depletion, debris ingestion, or physical deformation from a severe paper jam that was forcibly cleared. A seized cam will produce consistent C2154 regardless of CL5 or PS39 condition because the mechanism physically cannot complete the travel to the all-pressure position.
- M3 fusing motor failure or drive coupling problem. If M3 has failed or its drive coupling to the pressure cam system has broken, CL5 engaging will transmit no torque to the cam. The cam remains at the retraction position, PS39 does not change state, and C2154 is generated. M3 failure typically also produces a fusing fault code simultaneously. Confirm fusing function before suspecting M3 as the sole cause of C2154.
- Damaged harness between PS39/CL5 and the relay connectors or main board. A pinched, abraded, or fractured harness wire on the PS39 or CL5 signal paths produces intermittent or persistent C2154. This is more common on machines with high page counts where repeated maintenance access has disturbed harness routing, or on machines that have been moved and had rear panels or ITB assemblies removed and reinstalled multiple times.
- MFPB fuse blown (MFPB F13E on C227/C287; MFPB ICP2E on C258/C308/C368/C458). A blown MFPB fuse in the power path for CL5 or the PS39 supply circuit will prevent CL5 from engaging or PS39 from being read, producing C2154 without any mechanical fault. Fuse conduction must be verified before the MFPB is condemned.
- EXCB (Expansion Control Board) failure — C458/C558/C658 and C750i only. On models where CL5 routes through the EXCB, a failed EXCB output for CL5 means the clutch never receives its engagement signal even when the MFPB issues the command correctly. On these models, EXCB must be checked and potentially replaced before the MFPB.
- MFPB or BASEB failure. Board-level failure of the main control board’s PS39 input circuit or CL5 command output circuit is the least common root cause. Board replacement is always the final escalation step after all connector, sensor, clutch, and mechanical causes have been confirmed or eliminated.
Quick Reference — Troubleshooting by Symptom
| Symptom | Most Likely Cause | First Action |
|---|---|---|
| C2154 on first full-colour job after power-on; machine ran mono jobs successfully | PS39 or CL5 connector loose — only exposed when the all-pressure sequence is commanded for the first time; or PS39 contaminated | Check and reseat PS39 relay connector (CN24/CN113) and board-end connector; check and reseat CL5 relay connector (CN29/CN118) and board-end connector; clean PS39 sensor faces |
| C2154 intermittent — clears on power cycle then returns after several full-colour jobs | Intermittent relay connector in PS39 or CL5 path; marginal CL5 clutch engagement under thermal load | Reseat all connectors in PS39 and CL5 paths; check connector pin contacts for bent or pushed-back pins; monitor CL5 operation check across warm and cold conditions |
| C2154 with no audible cam mechanism movement when all-pressure sequence initiates | CL5 not engaging — connector open or CL5 coil failure; M3 not providing drive to the cam path | Reseat CL5 connector; perform CL5 operation check; verify M3 is running (confirm fusing function is operating); replace CL5 if operation check fails |
| C2154 with audible cam movement but C2154 still fires | PS39 sensor contaminated, misaligned, or failed; PS39 actuator flag bent or missing; PS39 connector open | Inspect PS39 physically; clean sensor faces; verify actuator flag position; perform PS39 I/O check |
| C2154 accompanied by a fusing fault code or fusing temperature error | M3 fusing motor failure — both fusing drive and transfer belt pressure cam share M3 as drive source | Perform M3 operation check; replace M3 if confirmed failed |
| C2154 alongside C2152 or other C215x codes simultaneously | Cam mechanism seized or heavily damaged — all cam position transitions fail; CL5 failure affecting entire cam sequence | Inspect cam mechanism manually for seizure or damage; check CL5 engagement; replace cam mechanism assembly or CL5 as appropriate |
| C2154 immediately after ITB unit or rear-side maintenance was performed | PS39 connector or CL5 connector not fully reseated after reassembly; PS39 physically displaced during panel removal | Trace all PS39 and CL5 connector paths; reseat every connector; confirm PS39 is correctly positioned in its mounting |
| C2154 persists after confirmed-good connector paths, clean PS39, and functioning CL5 | MFPB fuse blown (F13E on C227/C287; ICP2E on C258/C308/C368/C458); EXCB failure (C458/C558/C658/C750i); MFPB failure | Check MFPB fuse conduction; on C458/C558/C658/C750i, check EXCB CN8/CN14EX and consider EXCB replacement before MFPB |
Step-by-Step Diagnostic and Repair Procedure
⚠️ Warning: Switch the machine OFF at the main power switch and disconnect the power cord before performing any connector checks, mechanical inspections, or component replacements in the imaging engine area. The transfer belt, fusing unit, and surrounding area operate at high temperatures during printing. Allow at least 20 minutes after power-off before accessing internal imaging area components to avoid burns from the fusing unit. The intermediate transfer belt surface is sensitive — do not touch the belt surface with bare hands or tools, and do not use compressed air directly on the belt surface, as both will cause permanent image quality damage.
Step 1 — Confirm the Model Family and Record All Active Codes
- Identify the bizhub model and confirm the correct connector references from the affected models table before beginning any investigation. The relay connector labels (CN24 vs CN113 for PS39; CN29 vs CN118 for CL5) and the board-end connectors differ between the C227/C287 generation and the C258/C308/C368/C458/C558/C658 generation. Applying the wrong connector reference wastes diagnostic time.
- Record all active error codes. The presence of multiple C215x codes (C2152, C2153, C2154, C2155, C2156 together) indicates the cam mechanism has failed completely or that CL5 is not engaging at all, rather than a single-position sensor fault. Multiple simultaneous C215x codes focus investigation on CL5 and the cam mechanism itself before connectors and sensors.
- Note whether any fusing fault codes (e.g. C2411, C2412 range, or thermal fault codes) are also present alongside C2154. A concurrent fusing fault strongly suggests M3 motor failure as the root cause, since M3 drives both the fusing unit and the transfer pressure cam.
- Confirm whether the fault appeared during a full-colour print job (all-pressure sequence) or immediately at power-on initialisation. C2154 at power-on suggests a PS39 or CL5 connector was not properly seated during a previous reassembly. C2154 only during print jobs suggests a marginal sensor, clutch, or mechanical condition that only fails under operational load.
Step 2 — Inspect and Reseat All Connectors in the PS39 and CL5 Signal Paths
- Power the machine OFF and disconnect the power cord. Allow the fusing area to cool for at least 20 minutes before accessing the rear or side panels.
- Access the imaging engine area per the service manual procedure for your model. The PS39 sensor and CL5 clutch are located in the transfer belt pressure cam area, typically accessible via the right side or rear panels of the machine.
- Reseat the PS39 signal path connectors — all connection points, in order from the sensor outward to the control board:
- Connector at the PS39 sensor body.
- Relay connector:
- C227 / C287: relay CN24
- C258 / C308 / C368 / C458 / C558 / C658 / C450i / C550i / C650i / C750i: relay CN113
- C224 / C284 / C364 / C224e / C284e / C364e: relay CN113
- Board-end connector:
- C227 / C287: MFPB CN7E; signal pin: CN7E<B>-13 (ON)
- C258 / C308 / C368: MFPB CN15EB; signal pin: CN15EB-17 (ON)
- C458 / C558 / C658 / C450i / C550i / C650i: MFPB CN15E; signal pin: CN15EB-17 (ON)
- C750i: BASEB CN13E
- C224/C284/C364 / C224e/C284e/C364e: PRCB CN13; signal pin: CN13-7 (ON)
- Reseat the CL5 clutch signal path connectors — all connection points in order:
- Connector at the CL5 clutch body.
- Relay connector:
- C227 / C287: relay CN29
- C258 / C308 / C368 / C458 / C558 / C658 / C450i / C550i / C650i / C750i: relay CN118
- C224/C284/C364 / C224e/C284e/C364e: relay CN118
- Board-end connector:
- C227 / C287: MFPB CN12E; signal pin: CN12E-12 (ON)
- C258 / C308 / C368: MFPB CN15EA; signal pin: CN15EA-18 (ON)
- C458 / C558 / C658 / C450i / C550i / C650i: EXCB CN8
- C750i: EXCB CN14EX; also check EXCB CN2EX — BASEB CN12E (EXCB to BASEB communication connector)
- C224/C284/C364 / C224e/C284e/C364e: PRCB CN13; signal pin: CN13-14 (ON)
- Inspect all connector pins for bent contacts, pushed-back pins, toner contamination, or corrosion. Clean with isopropyl alcohol and a soft brush if contaminated.
- Reconnect power and attempt a full-colour print job. If C2154 does not recur, the fault was a connector seating issue — document and close.
Step 3 — Inspect and Clean PS39 (1st Transfer Pressure Sensor)
- Power the machine OFF and disconnect the power cord.
- Locate PS39 in the transfer belt pressure cam area. Refer to the service manual wiring diagram location for your model (22-C for C227/C287; 10-C for C258/C308/C368/C458).
- Inspect the PS39 sensor body for visible toner or paper dust contamination on its emitter and receiver faces. Even partial contamination can prevent the sensor beam from being interrupted by the cam flag, producing C2154 with a perfectly functional cam mechanism.
- Clean the PS39 sensor faces with a dry lint-free cloth or a cotton swab. Do not use solvents on the sensor body plastic.
- Inspect the PS39 actuator flag — the physical cam flag that enters the sensor beam path when the cam reaches the all-pressure position. Confirm:
- The flag is present and undamaged.
- The flag is correctly aligned to fully enter the PS39 beam path when the cam reaches the all-pressure position.
- The flag moves freely without catching on adjacent structures.
- With connectors reseated, reconnect power and perform the PS39 I/O check in service mode:
- C227 / C287: Control signal: MFPB CN7E<B>-13 (ON); Location: 22-C
- C258 / C308 / C368: Control signal: MFPB CN15EB-17 (ON); Location: 10-C
- C458 / C558 / C658: Control signal: MFPB CN15E (I/O); Location: 10-C
- C224/C284/C364 / C224e/C284e/C364e: Control signal: PRCB CN13-7 (ON); Location: 24-C
- C750i: Control signal: BASEB CN13E; refer to wiring diagram
- Manually move the cam flag into and out of the sensor beam while monitoring the PS39 signal. The signal should transition between ON (flag in beam) and OFF (flag clear of beam). If no transition occurs despite a clean sensor and confirmed connector, PS39 is failed — replace it.
Step 4 — Perform the CL5 Operation Check and Inspect the Cam Mechanism
- Reconnect power and enter Service Mode.
- Perform the CL5 operation check:
- C227 / C287: Control signal: MFPB CN12E-12 (ON); Location: 5-C
- C258 / C308 / C368: Control signal: MFPB CN15EA-18 (ON); Location: 8-C
- C458 / C558 / C658: Control signal: EXCB CN8; refer to wiring diagram for signal pin
- C224/C284/C364 / C224e/C284e/C364e: Control signal: PRCB CN13-14 (ON); Location: 23 to 24-C
- During the CL5 operation check, listen for the characteristic engagement sound of the electromagnetic clutch (a brief metallic click as the clutch plate engages). Absence of this sound while the operation check is running confirms CL5 is not engaging — either the coil is open or the mechanical clutch plate has failed.
- Power the machine OFF and disconnect the power cord. Manually rotate the cam mechanism by hand (with CL5 disengaged) to check for seizure or abnormal resistance. The cam should rotate smoothly through its full travel range. A cam that is seized, grinding, or requires excessive force to rotate has a mechanical fault in the cam body, gear, or cam follower that requires repair or replacement of the cam assembly.
- If CL5 does not engage during the operation check after connectors are confirmed seated, replace CL5. Refer to the service manual for the CL5 replacement procedure for your model.
Step 5 — Perform the M3 Operation Check
- Reconnect power and enter Service Mode.
- Perform the M3 operation check:
- C227 / C287: Control signal: MFPB CN11E-11 (REM), MFPB CN11E-14 (FGP); Location: 3-C
- C258 / C308 / C368 / C458 / C558 / C658: Control signal: MFPB CN8E-9 (REM), MFPB CN8E-12 (LOCK); Location: 2-C
- C224/C284/C364 / C224e/C284e/C364e: Control signal: PRCB CN2-9 (REM), PRCB CN2-12 (LOCK); Location: 27-I to J
- C750i: Refer to service manual for M3 operation check signal
- M3 should run smoothly during the operation check. The LOCK signal output confirms the motor is turning correctly (FG signal generated). An M3 that does not run, generates no LOCK signal, or runs with abnormal noise has failed — replace M3.
- Also confirm M3’s mechanical drive coupling to the fusing/pressure cam drive train is intact. Refer to the service manual for the M3 drive coupling inspection procedure for your model.
Step 6 — Check MFPB Fuse Conduction
- Power the machine OFF and disconnect the power cord.
- Access the MFPB and locate the relevant protective fuse:
- C227 / C287: MFPB F13E
- C258 / C308 / C368: MFPB ICP2E
- C458 / C558 / C658: MFPB ICP2E
- All other models: Refer to the service manual for the applicable fuse or ICP designation on the MFPB for the CL5 or PS39 supply circuit.
- Test fuse conduction with a multimeter in continuity mode. An open circuit (no continuity) confirms a blown fuse. Replace with an identical rated device — do not substitute a higher-rated fuse.
- Investigate why the fuse blew before reassembly. A blown MFPB fuse indicates an overcurrent event — typically caused by a shorted CL5 coil, a short in the PS39 supply harness, or a board fault. A replacement fuse will blow again immediately if the root cause is not addressed.
Step 7 — Check EXCB (C458/C558/C658/C750i Only)
- On models where CL5 routes through the EXCB (C458/C558/C658 via EXCB CN8; C750i via EXCB CN14EX), the EXCB must be checked before condemning the MFPB or BASEB.
- On the C750i, also check the EXCB CN2EX to BASEB CN12E communication connector. A loose connector on this EXCB-to-BASEB link can prevent CL5 commands from reaching the EXCB, producing C2154 without any fault in CL5 itself.
- On the C750i, also confirm CPUB (CPU board) is correctly seated. Refer to service manual for CPUB installation check procedure.
- If all connectors on the EXCB are confirmed seated and the EXCB output for CL5 (EXCB CN8 or CN14EX) is verified to be energizing correctly during the CL5 operation check but CL5 still does not engage, replace the EXCB. Replace the MFPB (or BASEB on C750i) only after EXCB replacement fails to resolve C2154.
Step 8 — Replace M3, EXCB, and/or MFPB/BASEB
- Replace components in the following order, verifying after each replacement before proceeding to the next:
- Replace M3 (fusing motor) if the M3 operation check confirmed motor failure.
- Replace EXCB (C458/C558/C658/C750i) if CL5 operation check confirmed the clutch is not receiving its command signal via the EXCB.
- Replace MFPB (or BASEB on C750i) as the final board-level step if all components and connectors have been confirmed and C2154 persists.
- After any board replacement, photograph all connector positions before removing the old board. Reconnect all harnesses in the same positions on the replacement board. Confirm each connector is fully locked before powering on.
- After board replacement, perform all three service mode checks (PS39 I/O check, CL5 operation check, M3 operation check) to confirm the replacement board drives and reads all three components correctly before running a full-colour test job.
Service Mode Reference — PS39, CL5, and M3 Checks by Model
| Model Group | Component | Control Signal | Wiring Diagram Location |
|---|---|---|---|
| C227 / C287 | PS39 (I/O check) | MFPB CN7E<B>-13 (ON) | 22-C |
| C227 / C287 | CL5 (operation check) | MFPB CN12E-12 (ON) | 5-C |
| C227 / C287 | M3 (operation check) | MFPB CN11E-11 (REM), MFPB CN11E-14 (FGP) | 3-C |
| C258 / C308 / C368 | PS39 (I/O check) | MFPB CN15EB-17 (ON) | 10-C |
| C258 / C308 / C368 | CL5 (operation check) | MFPB CN15EA-18 (ON) | 8-C |
| C258 / C308 / C368 | M3 (operation check) | MFPB CN8E-9 (REM), MFPB CN8E-12 (LOCK) | 2-C |
| C458 / C558 / C658 | PS39 (I/O check) | MFPB CN15E (I/O) | 10-C |
| C458 / C558 / C658 | CL5 (operation check) | EXCB CN8 | Refer to service manual |
| C458 / C558 / C658 | M3 (operation check) | MFPB CN8E-9 (REM), MFPB CN8E-12 (LOCK) | 2-C |
| C224 / C284 / C364 / -e variants | PS39 (I/O check) | PRCB CN13-7 (ON) | 24-C |
| C224 / C284 / C364 / -e variants | CL5 (operation check) | PRCB CN13-14 (ON) | 23 to 24-C |
| C224 / C284 / C364 / -e variants | M3 (operation check) | PRCB CN2-9 (REM), PRCB CN2-12 (LOCK) | 27-I to J |
| C750i | PS39 (I/O check) | BASEB CN13E | Refer to service manual |
| C750i | CL5 (operation check) | EXCB CN14EX | Refer to service manual |
| C750i | M3 (operation check) | Refer to service manual | Refer to service manual |
Understanding C2154 in the Context of the C215x Transfer Belt Pressure Code Family
C2154 belongs to a tightly coupled group of five codes that all involve PS39, CL5, and M3. Understanding each code’s specific detection condition prevents misidentification and guides more accurate root cause isolation:
- C2152 — Transfer belt fault at initial position return — PS39 cannot detect either the retraction-to-pressure or the pressure-to-retraction transition during the initial position return cycle at machine startup. This is the most severe member of the family — both transition directions fail, strongly suggesting the cam is physically seized or CL5 has completely failed.
- C2153 — Transfer belt spacing fault at K pressure switching — PS39 does not detect the switch from pressure to retraction (does not turn OFF) within the timeout after CL5 engages. The cam left the pressure position but could not reach the retraction position, or it reached retraction but PS39 did not confirm it.
- C2154 — Transfer belt contact fault at all pressure switching — this article. PS39 does not detect the switch from retraction to pressure (does not turn ON) within the timeout after CL5 engages during the all-colour pressure sequence. The cam could not reach the all-pressure position, or it reached it but PS39 did not confirm it.
- C2155 — Transfer belt contact fault after K pressure established — PS39 does not transition to the blocked state after the timeout expires once CL5 is deactivated following the pressure-complete signal. Indicates a maintained-contact confirmation failure rather than a transition failure during active cam travel.
- C2156 — Transfer belt spacing fault after all pressure established — PS39 is not unblocked after the timeout following CL5 deactivation when the spacing operation is complete. The cam reached the all-pressure position but could not confirm release.
The presence of multiple C215x codes simultaneously is the strongest indicator that the cam mechanism itself has seized or that CL5 has completely failed — conditions that prevent any cam transitions from occurring correctly. In this scenario, investigating PS39 and connectors first is less efficient than going directly to the CL5 operation check and cam mechanism physical inspection.
Rank B Reset Procedure
C2154 is classified as Rank B. The machine halts all printing — both colour and monochrome — and the fault must be resolved before any print output can resume.
- After completing the repair, power the machine OFF at the main power switch.
- Wait at least 10 seconds for all internal circuits to discharge fully.
- Power the machine ON and observe the machine during its startup initialization sequence. The transfer belt pressure mechanism will cycle through its initial position return routine at startup — the MFPB commands CL5 to engage and checks PS39 to confirm the mechanism initializes correctly. Confirm C2154 does not appear during this startup routine.
- Submit a full-colour test print (a multi-colour page, not a mono print) and observe the machine processing the first sheet. Confirm C2154 does not appear as the machine commands the all-pressure switching sequence for the first colour print.
- Print a minimum of 10 consecutive full-colour sheets to confirm stable operation across multiple pressure cycle transitions before returning the machine to service.
- Also submit a mono print job and then switch back to a colour job to confirm the machine correctly cycles between K-only pressure and all-pressure states repeatedly without generating any C215x codes.
Preventive Maintenance Recommendations
- Reseat relay connectors CN24/CN113 (PS39 path) and CN29/CN118 (CL5 path) at every PM visit — these relay connectors are located in the imaging engine area and are subject to progressive loosening from the vibration of the paper transport mechanism. A loose relay connector on either the PS39 or CL5 path is the single most common cause of C2154 and the most preventable with a 30-second reseat during PM.
- Clean PS39 at every PM visit — PS39 is directly adjacent to the imaging section and accumulates toner and paper dust at every print cycle. Cleaning the sensor faces during PM prevents the gradual contamination buildup that eventually causes a PS39 reading failure and C2154 between scheduled visits.
- Check CL5 engagement at major PM on high-volume colour machines — CL5 cycles between engaged and disengaged states on every transition between mono and colour printing. On machines with high colour print volumes or frequent mono-to-colour job switching, include a CL5 operation check in major PM to confirm the clutch is still engaging cleanly. A CL5 that is marginal in its engagement can cause intermittent C2154 that manifests only under specific thermal conditions.
- Inspect and lubricate the transfer belt pressure cam mechanism at extended PM intervals — the cam and its followers require adequate lubrication to travel smoothly through the full pressure and retraction range. On high-volume machines, cam lubrication depletes over time, increasing friction and eventually causing the cam to bind or seize. Refer to the service manual for the specified lubricant type and application points for the transfer belt pressure cam on your model — do not use general-purpose lubricants on precision cam surfaces.
- After any ITB unit replacement or rear-panel service, verify PS39 and CL5 connector seating before closing up — both PS39 and CL5 connectors are in areas that are accessed during ITB replacement and rear-panel removal. It is very easy to inadvertently unseat a relay connector during these service procedures. Making connector verification a mandatory final step before reassembly prevents a preventable C2154 on the machine’s first power-on after service.
Professional Technician Summary
Error Code C2154 is a transfer belt contact failure at the all-colour pressure switching stage: the 1st transfer pressure sensor PS39 did not confirm the switch from retraction to all-pressure within the allowed time after CL5 was commanded to engage. The three components directly involved — PS39, CL5, and M3 — share the same connector relay architecture across all affected models, meaning connector seating issues are always the highest-probability first cause and must be confirmed before any component is condemned.
In the field, the majority of C2154 calls are resolved by reseating the relay connectors in the PS39 signal path (CN24 on C227/C287; CN113 on C258 and later) and the CL5 clutch signal path (CN29 on C227/C287; CN118 on C258 and later), followed by cleaning the PS39 sensor faces. These two actions take less than 10 minutes and address the root cause of the vast majority of C2154 presentations without any parts replacement.
When hardware replacement is required, the escalation order is: replace CL5 (clutch failure — confirmed by failed CL5 operation check); replace M3 (motor failure — confirmed by failed M3 operation check, typically with concurrent fusing fault codes); check MFPB fuse conduction (F13E on C227/C287; ICP2E on C258/C308/C368/C458); replace EXCB on models where CL5 routes through the EXCB (C458/C558/C658/C750i); replace MFPB or BASEB as the final step.
Multiple simultaneous C215x codes (C2152 + C2154, or C2153 + C2154 + C2155) always point to a CL5 failure or a seized cam mechanism rather than multiple independent sensor or connector failures — investigate the shared mechanical cause before treating the individual codes as separate faults.