P0380
Glow Plug/Heater Circuit A
Glow plug / diesel preheat
Generic OBD-II
High
What it means
P0380 is a diesel code meaning the engine computer sees a fault in the glow-plug (intake/preheat) circuit A. Glow plugs warm the combustion chambers so a cold diesel will start; with a bad circuit, cold starts can be hard, rough, and smoky, though a warm engine usually runs normally. It's typically a burnt-out plug, wiring, or the control module.
High
Can I keep driving? A warm engine drives normally, but cold starts can be hard or fail entirely in cold weather until the glow-plug circuit is repaired. This is a diesel-only code.
Common symptoms
What you'll notice
- Check-engine light on (and often a glow-plug indicator light)
- Hard starting when the engine is cold
- Rough running or white smoke just after a cold start
- Little or no effect once the engine is warm
Common causes
Most likely first
- Burnt-out or open glow plug(s)Likely
- Damaged or corroded wiring in the glow-plug circuitCommon
- Loose or corroded electrical connectionsCommon
- Failed glow-plug control moduleLess often
- Failed ECM (rare — check plugs and wiring first)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and confirm which glow-plug circuit set the code.
- Inspect the glow-plug wiring, feed strap, and connectors for damage or corrosion.
- Measure each glow plug's resistance and replace any that are open or out of spec.
- Check the glow-plug control module output and its supply/ground.
- Repair the circuit or replace failed plugs, then clear and re-test with a cold start.
FAQ
Quick answers
Is it safe to drive with P0380?+
Yes, once it's running. The main effect is hard, smoky cold starts. Fix it before cold weather, when weak glow plugs make starting much harder.
Can I just clear P0380?+
It will return the next time the glow-plug circuit is tested unless a failed plug, wire, or module is repaired.
Related codes
Often seen with P0380
Read & clear P0380 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX