P1391 code meaning, causes and symptoms
P1391 means glow plug circuit low input (bank #1).
P1391 code meaning is one of the most common OBD-II searches when a warning light appears on the dashboard.
Drivers searching for P1391 usually want to know what the code means, whether the car is safe to drive and what part may need testing first.
Because P1391 can appear on multiple makes and models, it is important to combine the code meaning with live data, symptoms and any other stored faults.
A proper diagnosis for P1391 should normally include a scan tool check, freeze-frame review and inspection of the components related to glow plug circuit low input (bank #1).
Severity: Medium
Driving advice: Whether you can keep driving depends on how the vehicle is behaving. If there is rough running, loss of power, overheating or stalling, diagnose it as soon as possible.
FAQs
What does P1391 mean?
P1391 means glow plug circuit low input (bank #1).
What can cause P1391?
Causes can include failed components, wiring faults, leaks, pressure issues, bad readings or another upstream fault affecting the same system.
Is P1391 serious?
Severity depends on how the vehicle is behaving and what system is affected. Some codes are minor, while others can affect engine performance, emissions or drivability.