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SPN 788 FMI 7 — Clutch actuator not responding mechanically
SeriousTransmissionPower derate likely — plan to stop soon
Applies to: Eaton · Volvo · UltraShift PLUS common
Clutch actuator not responding mechanically.
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
- Failed clutch actuator
- Clutch worn out
- Mechanical bind
- Clutch actuator
- Clutch worn
- Linkage
First moves (roadside)
- Inspect clutch wear
- Check actuator
- Inspect clutch
- Actuator test
Common misdiagnoses
- Replacing actuator when clutch is worn
FAQ
What does SPN 788 FMI 7 mean?
Clutch actuator not responding mechanically.
How serious is SPN 788 FMI 7?
Serious — Power derate likely — plan to stop soon.
What's the most likely cause of SPN 788 FMI 7?
The most common cause is: Failed clutch actuator. Other possibilities include Clutch worn out; Mechanical bind; Clutch actuator; Clutch worn; Linkage.
Can I keep driving with SPN 788 FMI 7?
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.