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SPN 5585 FMI 31 — Engine derate active — parent fault
CautionEngineLimp to the next safe stop
Applies to: Detroit · Navistar · Paccar · Volvo
Engine derate active — parent fault.
Don't risk it — get a diesel tech on the truck.
Your SPN/FMI rides along, so nearby mechanics see the fault before they quote you.
How serious is it?
Caution. Limp to the next safe stop.
Most likely causes
- Parent fault commanding derate
- Parent fault
First moves (roadside)
- Find parent fault
- Find parent
FAQ
What does SPN 5585 FMI 31 mean?
Engine derate active — parent fault.
How serious is SPN 5585 FMI 31?
Caution — Limp to the next safe stop.
What's the most likely cause of SPN 5585 FMI 31?
The most common cause is: Parent fault commanding derate. Other possibilities include Parent fault.
Can I keep driving with SPN 5585 FMI 31?
Limp to the next safe stop. 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.