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P0380 — Glow Plug/Heater Circuit A
SeriousStarting/ColdPower derate likely — plan to stop soon
Seen on: Heavy Truck/Diesel
Glow Plug/Heater Circuit A. Common causes: Failed glow plugs.
Don't risk it — get a diesel tech on the truck.
Your code rides along, so nearby mechanics see the fault before they quote you.
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
What does P0380 mean?
Glow Plug/Heater Circuit A. Common causes: Failed glow plugs.
How serious is P0380?
Serious — Power derate likely — plan to stop soon.
What's the most likely cause of P0380?
The most common cause is: Failed glow plugs. Other possibilities include Timer module fault; wiring open.
Can I keep driving with P0380?
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 diesel engines (Cummins, Detroit, PACCAR, Volvo, Mack and more). Not a substitute for a scan-tool diagnosis on your specific truck.