P0380 — Glow Plug/Heater Circuit A
What it means: Glow Plug/Heater Circuit A.
How serious / can you keep driving: Serious. Power derate likely — plan to stop soon.
Check first: Test each glow plug resistance
Don't risk it — look up listed providers near you and give them this code when you call.
Listed providers nearest Ocala, FL
Closest first. Tell them P0380 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 Ocala, FL · (352) 830-1899
- 0.0 mi away — based in Ocala, FL · (352) 620-0740
- 0.0 mi away — based in Ocala, FL · (352) 497-0277
Seen on: Heavy Truck/Diesel
What P0380 means
Glow Plug/Heater Circuit A. Common causes: Failed glow plugs.
How serious is it?
Serious. Power derate likely — plan to stop soon.
Most likely causes
- Failed glow plugs
- Timer module fault
- wiring open
First moves (roadside)
- Test each glow plug resistance
- check timer relay
- inspect harness
FAQ
Glow Plug/Heater Circuit A. Common causes: Failed glow plugs.
Serious — Power derate likely — plan to stop soon.
The most common cause is: Failed glow plugs. Other possibilities include Timer module fault; wiring open.
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 P0380, 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)
Same symptom: Won't start or won't crank
Other codes that end in a truck that will not light off, especially cold.
- Intake air heater voltage high (SPN 729 FMI 3) · Engine
- Crankshaft/Camshaft Correlation Bank 1 Sensor A (P0016) · Engine
- Intake Air Heater Circuit Fault (P0540) · Engine
- Intake Air Heater Circuit Low (P0541) · Engine
- Intake Air Heater Circuit High (P0542) · Engine
- Battery voltage low during crank (SPN 168 FMI 17) · Electrical, Charging & Network
Find a mechanic or related guides
General diagnostic guidance for diesel engines (Cummins, Detroit, PACCAR, Volvo, Mack and more). Not a substitute for a scan-tool diagnosis on your specific truck.