OBD-II code P0671 indicates that the engine control module has detected an open circuit in the glow plug system for cylinder 1. An open circuit means the electrical path is broken, preventing the glow plug from heating the combustion chamber to assist in cold starting.
The internal heating element of the glow plug itself has burned out or fractured, creating an open circuit. This is the most common cause.
The electrical terminal connecting the wiring harness to the cylinder 1 glow plug is corroded, pushed back, or loose, breaking the electrical path.
The wire supplying voltage to the cylinder 1 glow plug has been physically damaged, rubbed through, or broken due to engine vibration and heat.
A failed glow plug control module or relay may not supply the necessary voltage to the specific cylinder, though this often affects multiple cylinders.
The engine computer has an internal driver failure preventing it from monitoring or powering the cylinder 1 glow plug circuit. This is extremely rare.
Yes, but you may experience difficult cold starts and rough idling until the engine reaches operating temperature. Prolonged driving with a dead glow plug can lead to unburned fuel washing the oil off the cylinder walls, causing premature wear.
Almost never. Mechanics or online advice sometimes jump to replacing the PCM, but the actual cause is almost always a failed glow plug, a corroded connector, or broken wiring.
When only one cylinder triggers an open circuit code, it typically points to an isolated failure of that specific glow plug or the individual wire feeding it, rather than a shared system component like a fuse or main relay.
While you can replace just the defective one to clear the code, it is generally recommended to replace all glow plugs at the same time. The others are likely the same age and will fail soon, and mismatched glow plugs can cause uneven combustion.