P0380: Glow Plug/Heater Circuit A
A generic powertrain (engine and transmission) trouble code, same meaning on every brand.
Yes once running - the problem is starting, especially in cold weather.
Symptoms
- Hard starting on cold mornings (diesel)
- Long cranking, white smoke at start
- Glow plug light behaving oddly
Likely causes, most common first
- One or more glow plugs burned out
- Glow plug controller or relay failed
- Wiring or busbar fault
- Blown fuse in the glow circuit
Read P0380 yourself before paying for diagnosis
A basic Bluetooth OBD-II scanner ($20-40) plugs into the port under the dashboard and shows this code with live sensor data on your phone - useful both for confirming the fix and for talking to a shop from an informed position.
What is going on and how it gets diagnosed
P0380 is the glow plug circuit on a diesel - the heaters that warm the combustion chambers so cold fuel will ignite. A summer diesel starts fine without them; the same truck at 20 degrees cranks endlessly and smokes white until it catches, because unburned fuel is fogging out of the exhaust.
Glow plugs are wear items that fail one at a time, and the engine tolerates the first casualty with barely a symptom. The code often arrives before the driver notices anything, which is the system working as intended - replacing plugs as a set at that point beats doing them individually each winter. On a high-mileage engine, a seized plug can snap during removal, so an experienced diesel shop and penetrating oil are worth more here than on most jobs.
Repair options and cost
Typical US independent-shop ranges, parts and labor. Dealers run higher; regional labor rates vary.
Frequently asked questions
Can I drive with P0380?
Yes once running - the problem is starting, especially in cold weather.
How much does it cost to fix P0380?
Typical US repair costs range from $20 for the simplest fix (fuse or relay) to $700 in the worst case. The right number depends on which cause your car has - see the causes list.
Related codes
The codes closest to P0380. They often appear together, and telling them apart is usually what narrows the diagnosis.
Definition per SAE J2012 standard nomenclature. Symptoms, causes and costs are editorial guidance - always confirm with a diagnosis of your specific vehicle.