P1391 Glow Plug Circuit Low Input Bank 1

Category: Powertrain - Fuel/Air Metering
Severity: Check Engine Light
Applies to: F-250/F-350 Super Duty diesel

What does P1391 mean on a Ford?

P1391 — Glow Plug Circuit Low Input Bank 1. This Ford-enhanced code applies to F-250/F-350 Super Duty diesel.

Common causes of P1391

Open bank 1 glow plug circuit
Failed bank 1 glow plugs
Faulty bank 1 relay
Corroded bank 1 bus connections
Controller fault

How to fix P1391

Test each bank 1 plug resistance
Check the bank 1 relay
Inspect bus bar connections
Verify controller command
Replace failed plugs or relay