P0382 indicates an electrical fault in the glow‑plug heater circuit B, which supplies power to one bank of glow plugs on a diesel engine. The PCM detects an open, short, or out‑of‑range voltage condition in that circuit and sets the code.
One or more of the glow plugs that belong to the B bank have an open or shorted heating element, causing the PCM to detect an abnormal circuit condition.
Damaged insulation, chafed wires, corroded pins, or loose connectors can create an open or short that the PCM interprets as a fault.
The fuse protecting the B‑bank glow‑plug circuit or the relay that switches power to those plugs may be open, preventing voltage from reaching the plugs.
If the vehicle uses a separate glow‑plug control module, its output driver for bank B can fail; alternatively, the PCM’s internal driver for that circuit can degrade.
A corroded ground strap or high‑resistance connection in the glow‑plug B return path can cause voltage drop that triggers the code.
Although sometimes suggested, a defective PCM is an uncommon cause; the PCM should only be considered after all wiring, plugs, fuses, relays, and any external control module have been verified good.
No. The PCM is rarely at fault for this code. Most P0382 cases are caused by a failed glow plug, wiring issue, blown fuse, or faulty relay. Only after those components have been tested and found good should the PCM be considered.
Yes. If the relay that supplies power to the B‑bank glow plugs is stuck open or has high resistance, the PCM will see an abnormal circuit and set the code.
The vehicle may start poorly, especially in cold weather, and could emit excess smoke. While short trips may be possible, prolonged operation can lead to hard starts and increased wear, so repairing the fault is recommended.
It is common practice to replace all glow plugs in the affected bank as a preventive measure, since they age similarly and accessing them often requires similar labor.