Jam Code 93-03 is a duplex transport section pre-feed obstruction fault on Konica Minolta bizhub machines with internal duplex printing capability. It belongs to the same 93-xx duplex transport section family documented for Jam Code 93-10, but where that code addresses a checkpoint-based transport failure of a sheet already committed to the duplex path, 93-03 addresses a condition detected before the current sheet is ever redirected into the duplex path at all — a pre-existing obstruction check, performed against the duplex unit’s own entrance/relay sensor chain, that failed before the switchback mechanism was ever commanded to send the current sheet into the duplex unit. This is the duplex-transport-section counterpart to the pre-feed obstruction logic already established elsewhere in this series for the second transfer section (30-03) and the paper exit section (32-06), applied here to the duplex unit’s internal path.
The official Konica Minolta description states precisely:
The duplex transport section’s entrance or internal relay sensor was detected in the blocked (ON) state during the pre-feed obstruction check performed before the switchback mechanism was commanded to redirect the current sheet into the duplex path. The engine board’s duplex-path clearance check failed.
Translated into field language: before the machine allows the switchback mechanism to redirect a freshly-fused sheet into the duplex unit for its second-side re-feed, the engine board performs a pre-feed check of the duplex transport section’s own sensor chain — confirming that no sheet, fragment, or obstruction is already sitting somewhere in that internal path from a previous job or a previous incompletely-cleared jam. This check happens before the switchback mechanism is activated for the current sheet. If the relevant duplex-path sensor already reads ON at this check point, the engine board withholds the switchback command for the current sheet and logs 93-03. In the large majority of 93-03 events, the current sheet never enters the duplex unit at all — depending on the specific machine’s design, it may be held at the switchback point, diverted directly to the output tray instead of being redirected for duplexing, or the job may simply halt — while the actual obstruction is found inside the duplex unit’s own internal transport path, left behind by an earlier job.
This distinction carries the identical diagnostic weight already established for its counterpart codes elsewhere in this series: 93-03 is not a statement about how the current sheet transported through the duplex path — it is a statement about what the machine found already sitting in that path before the current sheet was ever given the opportunity to enter it. A technician who receives a 93-03 call and immediately begins investigating the switchback mechanism’s own timing, the duplex re-feed rollers’ condition, or the pre-registration merge sensor — the correct diagnostic path for 93-10, 92-01, or 92-02 — is very likely investigating hardware that the current job never actually exercised. The correct first question for 93-03 is the same one established for every pre-feed obstruction code in this series: what is currently sitting in the duplex transport section that should not be there.
| Field | Details |
|---|---|
| Jam Code | 93-03 |
| KM Category Heading | Misfeed at Duplex Transport Section — the same 93-xx category documented for 93-10, covering the duplex unit’s internal reversal and relay path. Unlike 93-10, which describes a transport-behavior fault for a sheet already committed to the duplex path, 93-03 is a pre-feed obstruction check performed against the duplex transport section’s own sensor chain BEFORE the switchback mechanism is activated for the current sheet |
| What is and is not confirmed when 93-03 fires | Nothing about the current sheet’s duplex-path transport is confirmed either way, because in most cases the current sheet was never redirected into the duplex unit — the switchback command was withheld before it could be activated. What IS confirmed is that the relevant duplex-path sensor was reading ON at the moment the engine board performed its pre-feed clearance check — either from a genuine physical obstruction or from a sensor fault |
| Critical distinction from 93-10 | 93-10 (and the segmented-checkpoint family it belongs to) describes a sheet that HAS been redirected into the duplex path and then failed to complete transport through a specific monitored segment. 93-03 occurs BEFORE the current sheet is redirected at all — the pre-feed check found the duplex path already blocked and withheld the switchback command before the sheet ever entered the duplex unit |
| Critical distinction from 92-01 / 92-02 | 92-01 and 92-02 describe faults at the far end of the duplex journey — the pre-registration merge point — for a sheet that has already travelled through the duplex unit’s internal path. 93-03 occurs at the very beginning of that journey, before the sheet has entered the duplex unit at all. None of the pre-registration merge hardware is implicated in a 93-03 event |
| Detection Logic | Before commanding the switchback mechanism to redirect the current sheet into the duplex unit, the engine board reads the state of the duplex transport section’s entrance sensor and/or relevant internal relay sensor(s), per the model-specific pre-feed check logic. If the relevant sensor reads ON (blocked), the engine board withholds the switchback command for the current sheet, halts or redirects the job per the model’s specific handling of this condition, and logs 93-03. Refer to the model-specific SM to confirm exactly which sensor(s) this check monitors and how the current sheet is handled once the check fails (held at switchback, diverted to output tray, or job fully halted — this varies by model design) |
| What is physically found when 93-03 fires — three scenarios | (A) A paper fragment or a substantially intact sheet from a previous, incompletely-cleared duplex-area jam is physically present at or blocking the duplex transport section’s entrance or an internal relay sensor — the most common scenario. (B) No physical paper or fragment is found anywhere in the duplex transport section, but the relevant sensor reads ON in Service Mode with the path visually and physically clear — sensor stuck ON, from a jammed actuator, contamination, or electrical failure. (C) The current sheet is found at or near the switchback point, or already routed to the output tray instead of the duplex path (model-dependent), confirming the job’s duplex redirect was withheld before it was ever attempted — directing attention entirely to the duplex unit’s own internal path rather than to the switchback mechanism or the base machine’s exit hardware |
| Key Components | Duplex transport section entrance sensor and/or internal relay sensor(s) — exact designation and quantity vary by model and duplex unit design, refer to SM; the duplex unit’s internal transport path itself (reversal/relay rollers and guides, any intermediate checkpoint zones as documented for 93-10, and the path leading to the pre-registration merge point covered by 92-xx) — any of which can host a carried-over fragment; switchback mechanism (confirmed NOT activated for the current sheet in most 93-03 events, and therefore not itself a fault suspect, though its correct non-activation should be confirmed as part of Step 1); engine/duplex controller interface managing the pre-feed check logic and switchback command gating |
| Severity | High for duplex jobs specifically; simplex jobs are generally unaffected, since they do not use the duplex path or trigger this pre-feed check at all — confirming this scope early is a fast, useful diagnostic step; may recur immediately after a jam clearing that appeared complete but left a fragment behind somewhere within the duplex unit’s internal path — the most common field pattern for this code, consistent with every other pre-feed obstruction code documented in this series |
| Related Jam Codes | 93-10 (duplex transport section segmented checkpoint misfeed — a transport-behavior fault for a sheet already committed to the duplex path, as distinct from this pre-feed check), 92-01 / 92-02 (duplex pre-registration section — faults occurring further along the duplex journey, at the final merge point, for comparison), 30-03 (the functionally equivalent pre-feed obstruction check applied to the second transfer section rather than the duplex path), 32-06 (the functionally equivalent pre-feed obstruction check applied to the paper exit section) — refer to those articles for the same underlying diagnostic logic applied to different zones |
All Affected Models and Component References
Jam Code 93-03 applies to the same population of bizhub models and duplex unit hardware documented for 93-10 and the 92-xx family, since all of these codes reference the identical duplex unit internal path — the difference between 93-03 and its siblings is the point in the sequence at which the relevant sensor state is being evaluated. As with every duplex-related code in this series, exact sensor designations, connector references, and check codes are duplex-unit-specific and must be confirmed against the applicable model and duplex configuration’s own service manual.
| bizhub Models | Duplex Transport Entrance / Relay Sensor | Pre-Feed Check Logic Location | Sheet Handling on Check Failure | Primary Controlling Board |
|---|---|---|---|---|
| C250i / C300i / C360i / 250i / 300i / 360i | Refer to BASEB section of SM | BASEB firmware — pre-feed check performed prior to switchback command activation | Refer to SM (model-specific — held, diverted, or job halted) | BASEB |
| C3350i / C4000i / C4050i | Refer to BASEB section of SM | BASEB firmware | Refer to SM | BASEB |
| C258 / C308 / C368 / C227 / C287 / C367 | Refer to FRB section of SM | MFPB firmware, FRB I/O read | Refer to SM | MFPB + FRB |
| 368e / 308e / 458e / 558e / 658e | Refer to FRB / EXCB section of SM | MFPB firmware, FRB/EXCB I/O read | Refer to SM | MFPB + FRB + EXCB |
| C458 / C558 / C658 | Refer to EXCB / FRB section of SM | MFPB firmware, EXCB/FRB I/O read | Refer to SM | MFPB + FRB + EXCB |
| C450i / C550i / C650i / 458i / 558i / 658i | Refer to SM | Refer to SM | Refer to SM | MFPB + EXCB + FRB + BASEB |
| C224e / C284e / C364e / C224 / C284 / C364 / C454 / C554 | Refer to SM | Refer to SM | Refer to SM | PRCB / MFPB |
| 654e / 754e / 758 / 808 / 958 / PRO 958 / C659 / C759 | Refer to PFTDB / MFPB section of SM | Refer to SM | Refer to SM | PFTDB + MFPB |
All component references should be confirmed against the model-specific SM before any Service Mode check. The “sheet handling on check failure” column is intentionally marked “refer to SM” across every model in this table — unlike a simple abort, some duplex designs may attempt to divert the current sheet directly to the output tray rather than halting the job outright when the pre-feed check fails, and this behavior is genuinely model-specific. Confirming which behavior applies to the machine in front of you affects where you should expect to find the current sheet in Step 1.
ℹ️ The first two actions on every 93-03 call, before anything else: (1) Determine what happened to the current sheet — confirm from the SM whether this model diverts a check-failed sheet to the output tray or holds/aborts the job, then locate the sheet accordingly. In most cases it will not have entered the duplex unit at all. (2) With all paper removed from the duplex transport section, check the relevant sensor state directly in Service Mode. If the sensor reads OFF once the zone is confirmed clear, the fault was a genuine physical obstruction that has now been resolved — proceed to confirm no residual fragments remain (Step 3) and close out the call. If the sensor reads ON despite the zone being visibly and physically clear, the fault is a sensor problem, not a paper problem — proceed directly to sensor diagnosis (Step 4) without further searching for paper that is not there.
Understanding the Duplex-Path Pre-Feed Check — Why 93-03 Occurs
The pre-feed obstruction check that produces 93-03 exists for the same protective reason established for its counterparts at the second transfer section (30-03) and the paper exit section (32-06): the engine board will not commit a new sheet to a path that may already contain paper or debris from a previous event. For the duplex path specifically, this protection is particularly important because the duplex unit’s internal transport is typically more confined and more tightly curved than other transport zones (a consequence of the reversal geometry documented in the 93-10 article), meaning an existing obstruction has less clearance margin before it compounds into a more serious jam if a new sheet is driven into the same confined space.
The check itself is binary and pre-conditional, exactly as established for every pre-feed obstruction code in this series: it reads the current state of the relevant duplex-path sensor and either proceeds (clear) or withholds the switchback command entirely (blocked). It carries no information about the specific cause — only that the check failed — leaving the technician’s task to determine why the sensor was reading ON at the moment of the check.
Four root cause categories produce 93-03, ordered by frequency in field-installed bizhub duplex units, directly paralleling the category structure already established for 30-03 and 32-06 and applied here to the duplex-path-specific hardware:
- Category 1 — Paper fragment left behind from an incompletely-cleared previous jam within the duplex unit’s internal path (dominant cause by a wide margin): A previous jam anywhere within the duplex unit — at the switchback point, within the reversal path, or at the pre-registration merge point covered by 92-xx — was cleared, but a fragment was not fully removed. Given the duplex unit’s typically more confined and less immediately visible internal layout compared to the base machine’s main transport sections, fragments here are especially prone to being overlooked on a casual inspection. This category accounts for the substantial majority of 93-03 field events, with the identical diagnostic signature established for every pre-feed obstruction code in this series: the fault occurs on the very next duplex job attempted after a jam was cleared in or near the duplex unit
- Category 2 — Fragment or debris lodged specifically at the duplex transport entrance point: A more specific variant of Category 1, where the fragment sits right at the point where the switchback mechanism would redirect a new sheet into the duplex path — a location that, by its position at the very entrance to the duplex unit, is both a common trap point and one of the more accessible locations to inspect once the duplex access is open
- Category 3 — Duplex transport entrance/relay sensor stuck ON from actuator jam, contamination, or electrical failure (no physical paper present): The sensor has failed in the triggered state independent of any physical obstruction. Confirmed by Service Mode verification showing the sensor reading ON with the zone visually and physically confirmed completely clear
- Category 4 — Sensor harness or connector fault producing a false ON reading: A loose, corroded, or damaged harness connector between the sensor and the controlling/duplex-unit board can produce a signal interpreted as constant ON, independent of the sensor’s actual physical condition. Distinguished from Category 3 by testing the sensor directly at the sensor body where access allows
Step 1 — Determine Sheet Handling and Locate the Current Sheet
- Confirm from the model-specific SM how this machine handles a pre-feed check failure — whether the current sheet is diverted directly to the output tray instead of being redirected for duplexing, or whether the job is held/aborted with the sheet remaining at the switchback point
- Locate the current sheet accordingly. In the large majority of 93-03 events, the sheet will be found either already in the output tray (having been correctly diverted per the model’s design) or at the switchback point, never having entered the duplex unit’s internal path — confirming that the current sheet’s own transport is not the issue
- If the sheet is found in the output tray, no jam-clearing action is needed for it — it completed normally as a simplex-equivalent output, even though the job requested duplex. If the sheet is found held at the switchback point, remove it carefully following the model SM’s guidance
Step 2 — Inspect the Duplex Unit’s Internal Transport Path Thoroughly for Physical Obstruction
- Following the model SM access procedure, open access to the duplex unit’s internal transport path
- Inspect the entire accessible path systematically: the entrance point at the switchback junction, the internal reversal/relay path documented in the 93-10 article, and — where accessible without extensive disassembly — the approach toward the pre-registration merge point covered by 92-xx, using a flashlight at multiple angles
- Pay particular attention to the duplex transport entrance point specifically, given its status as the most common specific fragment location identified in Category 2
- Remove any fragment found using non-metallic tweezers, following the same careful technique established throughout this series for confined transport zones
- After removing any fragment, perform a second full inspection pass — a primary fragment often has smaller secondary fragments nested behind or beneath it
Step 3 — Verify the Sensor Reads OFF After Obstruction Removal
- With the zone visually confirmed clear, enter Service Mode and check the relevant duplex-path sensor state directly
- Sensor reads OFF: The physical obstruction removal has resolved the fault. Close all covers, run a 10-page duplex test job to confirm the machine now proceeds through the pre-feed check and completes normal duplex jobs without re-triggering 93-03. Document the fragment found in the service log
- Sensor still reads ON despite the zone being visually and physically confirmed completely clear: The cause is not a currently-present physical obstruction. Proceed to Step 4 without further time spent re-searching the same zone
Step 4 — Diagnose Sensor and Harness for a Stuck-ON Condition
- Inspect the actuator mechanism of the affected sensor, where the sensor type uses a physical actuator flag, confirming free range of motion and complete return to the home position — with particular attention to whether a small fragment may be lodged specifically at the actuator pivot rather than in the main paper path
- For transmissive sensor designs, inspect for contamination on the emitter/receiver windows and clean thoroughly
- Reseat the harness connector for the affected sensor at the controlling board or duplex unit’s own controller, whichever applies per the model SM
- Where test access allows, verify the sensor’s actual state directly at the sensor body to distinguish a genuinely failed sensor from a harness/connector fault
- If cleaning, actuator inspection, and harness reseating do not resolve the stuck-ON condition, replace the affected sensor per the model-specific SM. After replacement, verify correct toggle behavior in Service Mode before running a full duplex test job
Step 5 — Review Service History for a Recurrence Pattern
- Check the Error History log for whether 93-03 has occurred previously, and if so, whether each occurrence followed a jam clearing event in or near the duplex unit within a short time window
- If a clear pattern exists — 93-03 recurring specifically after jam clearings performed by customer operators — this points toward a training/process gap. Consider providing customer key operators with guidance on thoroughly inspecting the duplex unit’s internal path, not just the immediately visible jam location, as part of their standard jam-clearing routine
- If 93-03 has occurred multiple times with no clear connection to a preceding jam-clearing event, this points more strongly toward a recurring sensor or harness fault not yet fully resolved. Consider proactive sensor replacement if the pattern continues
Quick Reference — Troubleshooting by Symptom
| Symptom | Most Likely Cause | First Action |
|---|---|---|
| 93-03 on the first duplex job attempted immediately after clearing a previous jam in or near the duplex unit | Paper fragment left behind from the previous jam clearing — dominant cause, most often at the duplex transport entrance point | Inspect duplex transport entrance and internal path with flashlight at multiple angles; remove any fragment with non-metallic tweezers; verify sensor reads OFF in Service Mode after removal |
| 93-03 with the current sheet found in the output tray, not redirected for duplexing | This is the expected pattern on models that divert a check-failed sheet to output rather than holding the job — confirms the pre-feed check correctly withheld the switchback command | No action needed for the sheet itself; direct all further inspection to the duplex unit’s internal path |
| 93-03 with no paper found anywhere; relevant sensor reads ON in Service Mode with the zone visually confirmed completely clear | Sensor stuck ON — actuator jam, contamination, or electrical failure | Inspect actuator mechanism for a jam at the pivot point; clean sensor window; reseat harness connector; replace sensor if stuck-ON persists after these checks |
| 93-03 recurring specifically after jam clearings performed by customer operators, not after technician-performed clearings | Incomplete jam clearing within the duplex unit’s internal path by untrained operators — a process/training pattern rather than a hardware fault | Confirm the immediate fragment is cleared; provide customer key operators with guidance on thorough duplex-unit inspection as part of standard jam clearing |
| 93-03 recurring with no consistent connection to any preceding jam clearing event | Sensor or harness fault that returns intermittently despite prior cleaning or reseating | Re-inspect actuator and harness connector; test sensor directly at the sensor body if access allows; replace sensor proactively if the pattern continues |
Understanding the 93-xx Duplex Transport Section Jam Code Family
Jam Code 93-03 belongs to the 93-xx duplex transport section family documented for 93-10, now spanning both a checkpoint-based transport-behavior fault and a pre-condition check performed before the current sheet is even redirected into the duplex path:
- 93-03 — Duplex transport section pre-feed obstruction — the entrance/relay sensor was found already blocked during the pre-feed check performed before the switchback mechanism was commanded to redirect the current sheet. Not a transport failure of the current sheet; a pre-existing condition, almost always a fragment left behind from a previous event, or a sensor fault. The current sheet is typically found never having entered the duplex unit. This article
- 93-10 and higher — Segmented checkpoint faults for a sheet already committed to and transporting through the duplex path (refer to the 93-10 article for the checkpoint-based diagnostic approach)
93-03 is the duplex-transport-section counterpart to 30-03 (second transfer section) and 32-06 (paper exit section), and all three codes share identical diagnostic logic applied to different zones. As with those codes, recognizing that the current sheet is generally not the subject of the fault investigation is what separates an efficient 93-03 diagnosis from one that wastes time investigating switchback timing, duplex re-feed roller condition, or pre-registration merge hardware — none of which are relevant, because those systems were never given the opportunity to act on the current sheet.
Preventing Jam Code 93-03 From Recurring
- Provide customers with clear jam-clearing guidance specific to the duplex unit, emphasizing that the entire internal path — not just the immediately visible jam location — should be checked before closing any access panel, given the duplex unit’s typically more confined and less immediately visible internal layout
- When clearing any jam within the duplex unit as a technician, always perform the full flashlight, multi-angle inspection described in Step 2 as standard practice, not only when 93-03 has already occurred
- Include duplex transport entrance/relay sensor cleaning in every PM visit on machines with meaningful duplex volume
- Track recurrence patterns in the service log distinguishing jam-clearing-related 93-03 events from standalone, unexplained events, to determine whether the appropriate long-term fix is customer education or proactive sensor/harness replacement
Professional Technician Summary
Jam Code 93-03 is the duplex transport section pre-feed obstruction fault — the engine board’s routine check of the duplex path’s entrance/relay sensor, performed before it commands the switchback mechanism to redirect the current sheet, found the sensor already blocked and withheld the redirect before the current sheet ever entered the duplex unit. This is fundamentally different from 93-10 and from the 92-xx pre-registration codes: it is not a statement about how the current sheet transported through the duplex path, because in the large majority of cases the current sheet was never given the chance to enter that path at all.
The first action on every 93-03 call is determining what happened to the current sheet — confirm from the model SM whether a check-failed sheet is diverted to the output tray or held at the switchback point, then locate it accordingly. Either way, this correctly redirects all further attention to the duplex unit’s own internal path, not to the switchback mechanism, the base machine’s exit hardware, or the pre-registration merge zone, none of which are implicated.
The dominant cause, by a wide margin, is a paper fragment left behind from a previous duplex-area jam clearing. A thorough, multi-angle flashlight inspection of the duplex unit’s internal path — with particular attention to the transport entrance point — resolves the majority of 93-03 calls with no parts required. When the zone is genuinely and completely clear but the sensor continues to read ON, the fault has shifted from a paper problem to a sensor problem — trust the Service Mode reading and move directly to sensor and harness diagnosis rather than continuing to search a confirmed-clear zone.