Home › Fault codes › SPN 168 FMI 17
SPN 168 FMI 17 — Battery voltage low during crank
SeriousAbsPower derate likely — plan to stop soon
Applies to: Bendix · Detroit · Navistar · Paccar · Wabco
Battery voltage low during crank.
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
- Weak batteries
- Bad cables
- Alternator
- Bad cables/grounds
- Batteries
- Cables
First moves (roadside)
- Load test
- Cable voltage drop
- Alternator test
- Load test batteries and alternator
FAQ
What does SPN 168 FMI 17 mean?
Battery voltage low during crank.
How serious is SPN 168 FMI 17?
Serious — Power derate likely — plan to stop soon.
What's the most likely cause of SPN 168 FMI 17?
The most common cause is: Weak batteries. Other possibilities include Bad cables; Alternator; Bad cables/grounds; Batteries; Cables.
Can I keep driving with SPN 168 FMI 17?
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.