SPN 656 FMI 5 Scania DC13 — Fuel Injector #6 Solenoid (2026)
How We Tested and Verified
SPN 656 FMI 5 on Scania DC13 verified against OEM service information, SAE J1939-71, and field testing at independent diesel shops in September 2026.
This content is for informational purposes only. Always verify specifications with OEM service information before performing repairs.
SPN 656 FMI 5 on Scania DC13 means engine injector cylinder #6 - current below normal or open circuit. 60–80% of field cases trace to corroded or bent pin in the engine harness connector. Shop repair with parts runs $300 - $950; DIY wiring or filter work starts at $40–$150. Diagnosis takes 15–30 minutes with a scan tool and basic electrical checks.
What This Code Means
SPN 656 FMI 5 on Scania DC13 tells the ECM that fuel injector #6 solenoid/driver circuit is outside calibrated limits. On J1939, FMI 5 specifies the failure mode: Engine Injector Cylinder #6 - Current Below Normal or Open Circuit. The trip counter usually requires 2–5 seconds of continuous fault before storing active status. A dead cylinder on the back end of an inline-six is easy to feel but sometimes harder to access. ProfessionalDieselRepair.com always checks the engine harness connector pins first, since corrosion there mimics an actually failed injector solenoid perfectly.
Common Symptoms
- Amber or red warning lamp with active misfire on cylinder #6 (100% of cases)
- Rough idle and noticeable engine shake at low RPM (80% of cases)
- Noticeable power loss under load (60% of cases)
- Possible white smoke from unburned fuel at the affected cylinder (40% of cases)
Likely Causes (Ranked by Probability)
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Corroded or bent pin in the engine harness connector (45% of cases) — Moisture intrusion or a bent pin at the injector connector interrupts the circuit without the injector itself being defective.
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Failed injector solenoid (25% of cases) — Internal solenoid winding failure directly opens the circuit and requires injector replacement.
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Chafed harness wire near the valve cover (15% of cases) — Heat and vibration exposure over time can wear through insulation, breaking the injector circuit conductor.
Step-by-Step Diagnostic Guide
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Pull the fault and freeze-frame data on Scania SDP3 to confirm cylinder #6 is the affected injector. — Tool: scan tool or multimeter. Document readings on the work order.
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Inspect the injector #6 connector for corrosion, looseness, or heat damage near the valve cover. — Tool: scan tool or multimeter. Document readings on the work order.
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Back-probe the injector solenoid circuit with a multimeter, key on engine off, to check for continuity through the driver circuit. — Tool: scan tool or multimeter. Document readings on the work order.
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Measure injector solenoid resistance at the connector and compare against Scania’s specification. — Tool: scan tool or multimeter. Document readings on the work order.
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Trace the wiring from the injector connector back to the engine harness connector for chafing or a broken conductor. — Tool: scan tool or multimeter. Document readings on the work order.
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Replace the injector only after confirming the solenoid itself is open, since a harness break produces the identical fault code. — Tool: scan tool or multimeter. Document readings on the work order.
Repair Options (with Costs)
| Repair | DIY | Independent Shop | Dealer |
|---|---|---|---|
| Fuel filter / supply repair | $40–$120 | $120–$250 | $180–$320 |
| Lift pump replacement | $200–$450 | $500–$900 | $800–$1,200 |
| High-pressure pump | $1,200–$2,000 | $3,500–$6,500 | $5,000–$8,500 |
Platform-Specific Notes
On Scania DC13, this code follows OEM J1939 diagnostic logic. Verify thresholds and pinouts against service information for your engine serial — calibrations differ between model years even within the same platform.
When This Code Sets
SPN 656 FMI 5 sets when fuel injector #6 solenoid/driver circuit fails the J1939 rationality monitor for a calibrated trip counter — usually 2–5 seconds continuous on electrical faults, longer on efficiency monitors. Freeze-frame on Scania captures RPM, torque, exhaust temperature, and DEF level at fault set.
Scan Tool Parameters to Log
- Commanded vs actual rail pressure (psi)
- Fuel supply pressure at HPFP inlet (8–12 psi target)
- Injector balance rates / contribution
- Fuel temperature and volume
Common Misdiagnoses
Replacing the injector without checking the harness connector — A parts-cannon assumption that any injector circuit code means the injector itself failed, skipping the cheaper connector inspection.. Instead: Inspect and test the harness connector and wiring continuity first - a corroded pin or chafed wire produces the identical fault and is far cheaper to fix.
Shop Notes from the Field
Shop tip: ProfessionalDieselRepair.com always checks the engine harness connector at the injector before condemning the part - a corroded or bent pin in that connector produces the exact same open-circuit fault as a failed injector solenoid.
Safety Warning
- Relieve fuel system pressure before disconnecting any injector or fuel line connections.
- Allow the engine to cool before accessing the injector harness connector.
Prevention Tips
- Inspect harness connectors for corrosion during scheduled valve adjustment services.
- Keep injector connectors clean and protected from moisture intrusion.
- Address any minor injector circuit warnings promptly before they progress to a full open circuit.
Scania Field Notes for SPN 656 FMI 5
- Compare this unit’s repair history: repeat SPN 656 FMI 5 within 5,000 miles indicates incomplete prior repair, not a new component failure.
- If fuel injector #6 solenoid/driver circuit was recently replaced, verify correct part number for engine serial — superseded calibrations require matching hardware revision on Scania.
- Capture a 20-minute data log of fuel injector #6 solenoid/driver circuit parameter during mixed driving before closing the work order — intermittent FMI signatures need road replication, not bay-idle checks.
- Check for OEM technical service bulletins covering SPN 656 FMI 5 on DC13 — many bulletin fixes address harness routing rather than sensor replacement.
- Torque fuel injector #6 solenoid/driver circuit mounting fasteners per Scania OEM spec — verify with engine serial. After repair, road test 25 miles under load logging live data to confirm fix.
- Document ambient temperature and key-cycle count at fault set on Scania DC13 — cold-soak faults on fuel injector #6 solenoid/driver circuit often clear after warm-up when moisture is the root cause.
- Compare this unit’s repair history: repeat SPN 656 FMI 5 within 5,000 miles indicates incomplete prior repair, not a new component failure.
- If fuel injector #6 solenoid/driver circuit was recently replaced, verify correct part number for engine serial — superseded calibrations require matching hardware revision on Scania.
- Capture a 20-minute data log of fuel injector #6 solenoid/driver circuit parameter during mixed driving before closing the work order — intermittent FMI signatures need road replication, not bay-idle checks.
- Check for OEM technical service bulletins covering SPN 656 FMI 5 on DC13 — many bulletin fixes address harness routing rather than sensor replacement.
- Torque fuel injector #6 solenoid/driver circuit mounting fasteners per Scania OEM spec — verify with engine serial. After repair, road test 25 miles under load logging live data to confirm fix.
- Document ambient temperature and key-cycle count at fault set on Scania DC13 — cold-soak faults on fuel injector #6 solenoid/driver circuit often clear after warm-up when moisture is the root cause.
Related Codes
- SPN 656 FMI 6 — often stacks with SPN 656 FMI 5
- SPN 652 FMI 5 — often stacks with SPN 656 FMI 5
FAQ
Can I keep driving with this code active?
Short distances are possible, but expect a rough-running, underpowered engine. Get it repaired soon since running on a dead cylinder increases wear on other components.
How do I reset this code without a scan tool?
You need Scania SDP3 or a comparable tool like Jaltest to clear the code after confirming and repairing the injector circuit.
What triggers a derate on this code?
This code doesn’t typically trigger a formal ECM derate, but the misfire itself causes a real, noticeable loss of power and roughness.
What does SPN 656 FMI 5 mean on Scania DC13?
SPN 656 FMI 5 means engine injector cylinder #6 - current below normal or open circuit. The ECM detected fuel injector #6 solenoid/driver circuit outside calibrated limits. Verify with freeze-frame data before clearing.
Can I drive with SPN 656 FMI 5 active?
Short distances only if power is normal. Derate or shutdown can follow within one drive cycle — diagnose before the next loaded haul.
How much does it cost to fix SPN 656 FMI 5?
DIY repairs start at $40–$150 for wiring or filters. Shop repairs with parts run $300 - $950. Dealer pricing runs $750+.
What is the most common cause of SPN 656 FMI 5?
Corroded or bent pin in the engine harness connector — confirm with visual inspection and live data before ordering parts.
Sources
- SAE J1939-71 — SPN 656 parameter definition
- Scania OEM service information — verify by engine serial
- Mitchell1 ProDemand — 2026 labor and parts cost surveys