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SPN 656 FMI 5 — Injector #6 open circuit
SeriousEnginePower derate likely — plan to stop soon
Applies to: Navistar · Paccar · Volvo
Injector #6 open circuit.
Don't risk it — get a diesel tech on the truck.
Look up listed providers near you and give them this SPN/FMI when you call.
How serious is it?
Serious. Power derate likely — plan to stop soon.
Most likely causes
- Open coil
- Harness
- Connector
First moves (roadside)
- Resistance
- Swap
- Resistance and swap
FAQ
What does SPN 656 FMI 5 mean?
Injector #6 open circuit.
How serious is SPN 656 FMI 5?
Serious — Power derate likely — plan to stop soon.
What's the most likely cause of SPN 656 FMI 5?
The most common cause is: Open coil. Other possibilities include Harness; Connector.
Can I keep driving with SPN 656 FMI 5?
Power derate likely — plan to stop soon. When in doubt, get a qualified mobile diesel tech on the truck before continuing.
Throwing this code right now?
Find a mechanic or related guides
General diagnostic guidance for heavy-duty diesel engines (Cummins, Detroit, PACCAR, Volvo, Mack). Not a substitute for a scan-tool diagnosis on your specific truck.