P0380: Glow Plug/Heater Circuit \"A\" Malfunction
Severity: medium
What it means: The engine computer sees a problem in the glow plug circuit. Glow plugs heat the cylinders so a diesel starts easily when cold.
Safe to drive? Yes, usually. The engine may be hard to start when cold and may smoke at startup, but glow plugs don't affect driving once it's running.
Common symptoms
- Hard starting or long cranking when cold
- White smoke at cold startup
- Check engine light
- Often shows up with cylinder glow plug codes like P0673 or P0674
Likely causes, ranked
- Failed glow plug control moduleDIY
- Failed glow plugsDIY
- Damaged wiring or connectorDIY
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Vehicle-specific notes
- 2003–2018 Freightliner Sprinter: A 2006 Freightliner Sprinter owner had P0380 along with P0673 and P0674 on cold starts. Owners said to replace the glow plugs first and then the controller if codes returned. Read the full answer · Source
DIY or shop?
DIY for careful owners: glow plugs and the module are reachable on many diesels. A glow plug that snaps in the head is a shop job.
Before you replace parts
- Read all stored codes and note which cylinders are listed.
- Check the glow plug connectors and wiring for damage or corrosion.
- Test the glow plug's resistance before replacing it.
- If codes for several cylinders show up or keep moving, test the glow plug control module.
- Clear the codes after the repair and confirm they stay off on the next cold start.
Safety / mechanic note
Verify with a mechanic. A code points to a system, not always a specific part.
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