SPN 1127 FMI 0 — Turbo boost pressure high
What it means: Turbo boost pressure high.
How serious / can you keep driving: Serious. Power derate likely — plan to stop soon.
Check first: Compare live data
Don't risk it — look up listed providers near you and give them this SPN/FMI when you call.
Listed providers nearest Louisville, KY
Closest first. Tell them SPN 1127 FMI 0 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 Louisville, KY · (502) 773-1159
- 0.0 mi away — based in Louisville, KY · (502) 447-1234
- 0.0 mi away — based in Louisville, KY · (502) 648-6725
Applies to: Navistar · Paccar · Volvo
What SPN 1127 FMI 0 means
Turbo boost pressure high.
How serious is it?
Serious. Power derate likely — plan to stop soon.
Most likely causes
- Overboost
- Stuck VGT
- Stuck VGT vanes
- VGT stuck
First moves (roadside)
- Compare live data
- Live data compare
- Actual vs commanded
FAQ
Turbo boost pressure high.
Serious — Power derate likely — plan to stop soon.
The most common cause is: Overboost. Other possibilities include Stuck VGT; Stuck VGT vanes; VGT stuck.
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 1127 FMI 0, or share the same subsystem.
- Turbo Boost Pressure — High / Overboost (SPN 1127 FMI 16)
- Engine Protection — Power Derate Active (SPN 1569 FMI 31)
- Intake Manifold (Charge Air) Temp — High (SPN 105 FMI 0)
- 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)
Same symptom: Low boost / low power
Other air-path codes that arrive as a truck that will not pull the hill it pulled yesterday.
- Turbo compressor inlet temp high voltage (SPN 1172 FMI 3) · Engine
- Turbo compressor inlet pressure — high voltage (SPN 1176 FMI 3) · Engine
- VGT actuator position — not responding (SPN 2795 FMI 7) · Engine
- VGT position — not responding (similar to 2795) (SPN 5571 FMI 7) · Engine
- Turbo turbine inlet temp — high voltage (SPN 5856 FMI 3) · Engine
- Turbocharger 1 Wastegate/VGT Actuator - Mechanical System Not Responding Properly (VGT vanes stuck / not tracking commanded position) (SPN 641 FMI 7) · Engine
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.