SPN 723 FMI 8 — Cam position sensor — abnormal signal
What it means: Cam position sensor — abnormal signal.
How serious / can you keep driving: Serious. Power derate likely — plan to stop soon.
Check first: Check air gap and connector
Don't risk it — look up listed providers near you and give them this SPN/FMI when you call.
Listed providers nearest Billings, MT
Closest first. Tell them SPN 723 FMI 8 and what the truck is doing. RoadService.app lists these providers and does not employ them or carry out the repair.
- 0.0 mi away — based in Billings, MT · (406) 245-8985
- 0.0 mi away — based in Billings, MT · (406) 252-8413
- 0.0 mi away — based in Billings, MT · (406) 780-3711
Applies to: Detroit · Paccar
What SPN 723 FMI 8 means
Cam position sensor — abnormal signal.
How serious is it?
Serious. Power derate likely — plan to stop soon.
Most likely causes
- Failing cam sensor
- Tone wheel
- Wiring
- Sensor
- Air gap
First moves (roadside)
- Check air gap and connector
- Inspect sensor
FAQ
Cam position sensor — abnormal signal.
Serious — Power derate likely — plan to stop soon.
The most common cause is: Failing cam sensor. Other possibilities include Tone wheel; Wiring; Sensor; Air gap.
Power derate likely — plan to stop soon. When in doubt, get a qualified mobile diesel tech on the truck before continuing.
Related codes
Codes that commonly appear alongside SPN 723 FMI 8, or share the same subsystem.
- Engine Protection — Power Derate Active (SPN 1569 FMI 31)
- Intake Manifold (Charge Air) Temp — High (SPN 105 FMI 0)
- Turbo Boost Pressure — High / Overboost (SPN 1127 FMI 16)
- Boost pressure high (SPN 102 FMI 0)
- Boost sensor — voltage low (SPN 102 FMI 4)
- Intake manifold temp — voltage high (SPN 105 FMI 3)
- Intake manifold temp — voltage low (SPN 105 FMI 4)
- Injection control pressure low (HEUI — older engines) (SPN 164 FMI 1)
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.