P0380: Glow plug/heater circuit "A" malfunction
A glow plug or its control circuit has a fault. Cold starts on a diesel get harder.
Updated
What P0380 means
A diesel engine ignites its fuel by compression alone. When the engine is cold, glow plugs heat the combustion chambers so that it starts easily. On many engines they stay on briefly after starting, to smooth the cold running.
A relay or control module switches the glow plugs, and the engine computer checks the circuit. P0380 means it found a fault in glow plug circuit “A”.
P0382, P0383, P0384 and P0670 to P0684: other glow plug codes
P0382 is the same fault in glow plug circuit “B”. P0671 to P0682 name the cylinder whose glow plug or wiring has a fault: P0671 is cylinder 1, P0679 cylinder 9, and P0680 to P0682 are cylinders 10 to 12. P0383, P0384 and P0670 concern the circuit that switches the control module, and P0683 and P0684 the link between the module and the engine computer. Their own meaning and causes are shown below.
A faulty control module can also keep the glow plugs on for too long, which burns them out early, so the module codes are a check soon, not a wait until the next inspection.
P0382: Glow Plug/Heater Circuit B
P0383: Glow Plug Control Module 1 Control Circuit Low
The circuit the engine computer uses to switch the glow plug control module has a fault, so the glow plugs may not heat when they should. Cold starts on a diesel get harder.
Common causes: faulty glow plug control module, wiring or connector fault, blown fuse.
Driving: Probably OK to drive short-term, but have it checked soon. A faulty glow plug control module can leave the glow plugs on for too long, which burns them out, and in frost the engine may be hard or impossible to start.
P0384: Glow Plug Control Module 1 Control Circuit High
The circuit the engine computer uses to switch the glow plug control module has a fault, so the glow plugs may not heat when they should. Cold starts on a diesel get harder.
Common causes: faulty glow plug control module, wiring or connector fault, blown fuse.
Driving: Probably OK to drive short-term, but have it checked soon. A faulty glow plug control module can leave the glow plugs on for too long, which burns them out, and in frost the engine may be hard or impossible to start.
P0670: Glow Plug Control Module 1 Control Circuit/Open
The circuit the engine computer uses to switch the glow plug control module has a fault, so the glow plugs may not heat when they should. Cold starts on a diesel get harder.
Common causes: faulty glow plug control module, wiring or connector fault, blown fuse.
Driving: Probably OK to drive short-term, but have it checked soon. A faulty glow plug control module can leave the glow plugs on for too long, which burns them out, and in frost the engine may be hard or impossible to start.
P0671: Cylinder 1 Glow Plug Circuit/Open
The glow plug of the cylinder in the code, or its wiring, has a fault. Cold starts on a diesel get harder.
Common causes: burnt-out glow plug, wiring or connector fault at the plug, faulty glow plug control module.
P0672: Cylinder 2 Glow Plug Circuit/Open
The glow plug of the cylinder in the code, or its wiring, has a fault. Cold starts on a diesel get harder.
Common causes: burnt-out glow plug, wiring or connector fault at the plug, faulty glow plug control module.
P0673: Cylinder 3 Glow Plug Circuit/Open
The glow plug of the cylinder in the code, or its wiring, has a fault. Cold starts on a diesel get harder.
Common causes: burnt-out glow plug, wiring or connector fault at the plug, faulty glow plug control module.
P0674: Cylinder 4 Glow Plug Circuit/Open
The glow plug of the cylinder in the code, or its wiring, has a fault. Cold starts on a diesel get harder.
Common causes: burnt-out glow plug, wiring or connector fault at the plug, faulty glow plug control module.
P0675: Cylinder 5 Glow Plug Circuit/Open
The glow plug of the cylinder in the code, or its wiring, has a fault. Cold starts on a diesel get harder.
Common causes: burnt-out glow plug, wiring or connector fault at the plug, faulty glow plug control module.
P0676: Cylinder 6 Glow Plug Circuit/Open
The glow plug of the cylinder in the code, or its wiring, has a fault. Cold starts on a diesel get harder.
Common causes: burnt-out glow plug, wiring or connector fault at the plug, faulty glow plug control module.
P0677: Cylinder 7 Glow Plug Circuit/Open
The glow plug of the cylinder in the code, or its wiring, has a fault. Cold starts on a diesel get harder.
Common causes: burnt-out glow plug, wiring or connector fault at the plug, faulty glow plug control module.
P0678: Cylinder 8 Glow Plug Circuit/Open
The glow plug of the cylinder in the code, or its wiring, has a fault. Cold starts on a diesel get harder.
Common causes: burnt-out glow plug, wiring or connector fault at the plug, faulty glow plug control module.
P0679: Cylinder 9 Glow Plug Circuit/Open
The glow plug of the cylinder in the code, or its wiring, has a fault. Cold starts on a diesel get harder.
Common causes: burnt-out glow plug, wiring or connector fault at the plug, faulty glow plug control module.
P0680: Cylinder 10 Glow Plug Circuit/Open
The glow plug of the cylinder in the code, or its wiring, has a fault. Cold starts on a diesel get harder.
Common causes: burnt-out glow plug, wiring or connector fault at the plug, faulty glow plug control module.
P0681: Cylinder 11 Glow Plug Circuit/Open
The glow plug of the cylinder in the code, or its wiring, has a fault. Cold starts on a diesel get harder.
Common causes: burnt-out glow plug, wiring or connector fault at the plug, faulty glow plug control module.
P0682: Cylinder 12 Glow Plug Circuit/Open
The glow plug of the cylinder in the code, or its wiring, has a fault. Cold starts on a diesel get harder.
Common causes: burnt-out glow plug, wiring or connector fault at the plug, faulty glow plug control module.
P0683: Glow Plug Control Module 1 to PCM Communication Circuit
The glow plug control module and the engine computer can’t exchange their signals properly, so the glow plugs may not be switched when they should. Cold starts on a diesel get harder.
Common causes: faulty glow plug control module, wiring or connector fault between the module and the engine computer, low battery voltage.
P0684: Glow Plug Control Module 1 to PCM Communication Circuit Range/Performance
The glow plug control module and the engine computer can’t exchange their signals properly, so the glow plugs may not be switched when they should. Cold starts on a diesel get harder.
Common causes: faulty glow plug control module, wiring or connector fault between the module and the engine computer, low battery voltage.
Can I keep driving?
Likely OK to drive
Likely OK to drive for now. Have it fixed before the next emissions inspection: an inspection that reads OBD, such as the Dutch APK, sees the code.
General guidance based on the code alone, not on the car’s actual condition. If in doubt, stop and ask a mechanic.
In mild weather many diesels still start, but in frost a car with failed glow plugs can be hard or impossible to start.
Symptoms
- Harder starting when cold, with longer cranking.
- White or blue smoke and rough running just after a cold start.
- On some cars, the glow plug light flashes or stays on.
Common causes
- Burnt-out glow plug. Glow plugs wear out. When one fails, others of the same age may not be far behind.
- Faulty glow plug relay or control module. It switches the current to the plugs. If it fails, none of them heat.
- Wiring fault. A loose or corroded connector at a plug or the module.
Typical fixes
- Have each glow plug tested, by its resistance or current draw, to find the ones that failed.
- Replace the failed plugs. On many engines they can seize in the cylinder head, so removing them is a job for a workshop.
- Have the relay or control module and the wiring checked if the plugs test fine.
- Clear the code after the repair and check the next cold start.
Questions
Can I drive with P0380?
Likely, for now: the app’s advice is that it’s likely OK to drive, and to have it fixed before the next emissions inspection. Expect harder cold starts, especially in frost.
Does the car need new glow plugs?
Not necessarily. A test shows whether a plug, the relay or control module, or the wiring is at fault. Replace only what failed, or all of them if a workshop advises it because of their age.