P0380 fault code: glow plug circuit problem
Plain-language definition
Glow Plug/Heater Circuit A
What does it mean?
In a diesel engine, the fuel isn't ignited by a spark plug but by the heat of the compressed air. Because that heat may not be enough when the engine is cold, most diesel engines have a glow plug in each cylinder; the glow plugs heat the combustion chamber before the engine is started and for a while after it starts. Some engines also use a heater that warms the intake air.
The engine computer controls the current to the glow plugs through a glow plug relay or control module. P0380 is stored when the engine computer sees an unexpected electrical condition in this circuit (circuit A); for example, the circuit may be interrupted (open circuit) because of a broken wire or a burned-out glow plug, or there may be a short circuit somewhere.
The most obvious symptom is the engine being slow or hard to start, especially in cold weather. In the first few minutes after starting, you may notice the engine running unevenly, misfiring or blowing white smoke from the exhaust. The check engine light may come on; on some cars the glow plug light with the coil symbol may flash.
How serious is it?
It's shown as Priority because the glow plug system is needed for a diesel engine to start in the cold. As the problem gets worse, the engine may not start at all, especially in cold weather.
Severity is a guide; if the warning light is flashing or you notice symptoms while driving, have the car checked at a workshop.
Common general causes
- One or more glow plugs at the end of their life (burned out)
- A glow plug wire or connector that is loose, broken or corroded
- A faulty glow plug relay or control module
- A short in the circuit, or a blown fuse
- Less often, problems coming from the engine computer (ECU)
The list shows general causes; a workshop finds the actual cause on your car with a check.
Definitions by make
Some manufacturers record the same code under their own wording:
- Fiat
- Command preheating control relay,
Related codes
How does it appear in the 2dakika report?
Glow Plug/Heater Circuit A
If the code is read as a confirmed (stored) fault, the report shows it with the "Priority" severity; in pending or past records, codes that don't request the warning light and aren't critical appear as "Info". If the engine computer stored them, the conditions when the fault was recorded (engine temperature, rpm, speed) are shown too.
Read this code with the OBD-X1, and clear it from the app after the repair.
Clearing the code doesn't fix the fault; if the problem persists, the code comes back.