P1391
Glow Plug Circuit Low Input (Bank #1)
P1391 is an OBD-II diagnostic trouble code meaning: Glow Plug Circuit Low Input (Bank #1). Common causes: faulty glow plug, open or short circuit in the glow plug circuit. Estimated repair cost: $9–39.
Symptoms
- Difficulty starting the engine (especially in cold weather)
- Unstable engine operation after starting
- Increased exhaust smoke
- Check Engine Light on Dashboard
- Reduced engine power
Causes
- Faulty glow plug
- Open or short circuit in the glow plug circuit
- Problems with the relay or glow plug control module
- Contact corrosion
- Malfunction of the engine control unit (rare)
How to Fix
- Check the resistance of the glow plugs
- Inspect wiring and connectors for damage
- Check the voltage at the glow plugs
- If necessary, replace faulty glow plugs
- Check and, if necessary, replace the glow plug relay
Related codes
Error P1391 by Vehicle Brand
FAQ
What does the P1391 code mean?
P1391 is an OBD-II diagnostic trouble code that indicates: Glow Plug Circuit Low Input (Bank #1)
What causes a P1391 error code?
The most common causes of P1391 include: Faulty glow plug; Open or short circuit in the glow plug circuit; Problems with the relay or glow plug control module; Contact corrosion.
How do I fix a P1391 diagnostic trouble code?
To fix P1391: Check the resistance of the glow plugs. Inspect wiring and connectors for damage. Check the voltage at the glow plugs. For a complete diagnosis, use an OBD-II scanner.
Is it safe to drive with P1391?
Yes, but get it checked soon
How much does it cost to fix P1391?
The estimated repair cost for P1391 is $9–39. Actual cost depends on your vehicle, location, and labor rates.
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