Glow Plug Circuit Low Voltage (Bank 1)
The POWERSTROKE-P1391 (Power Stroke) diesel fault code means: Glow Plug Circuit Low Voltage (Bank 1). This is a moderate severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- intermediate
- Estimated cost
- $100-$500
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View pilot availability →What Are the Symptoms of POWERSTROKE-P1391?
- Hard cold start
- White smoke
- CEL
What Causes POWERSTROKE-P1391? (Most Likely First)
- Failed bank 1 glow plugs Very Likely
- Valve cover gasket harness damage Likely
- GPR contact failure Possible
Can I Still Drive with POWERSTROKE-P1391?
Yes, but fix soon. POWERSTROKE-P1391 is rated moderate severity. It is not an immediate stop-driving fault, but it will not clear itself — book the repair rather than ignoring it.
Frequently Asked Questions
What is P1391 on a 7.3L Power Stroke?
P1391 on a 7.3L Power Stroke (1994-2003) indicates: Glow Plug Circuit Low Voltage (Bank 1). This is a known diagnostic trouble code on this engine family and typically points to the causes listed above.
Can I drive with P1391 on my Power Stroke?
Yes, you can generally drive with this code, but diagnose it soon to prevent further damage.
How much does it cost to fix P1391?
Repair cost is typically $100-$500 depending on the underlying cause and whether you DIY or use a shop. Diagnostic time alone runs $100-$180 at most independent diesel shops.
Mechanics Guide Step-by-step diagnosis
How Do You Diagnose POWERSTROKE-P1391?
Perform individual glow plug resistance test on bank 1.
Inspect UVCH harness; replace valve cover gasket assembly if damaged.
P1391 on Other Platforms
The same code ID appears across other engines, vehicles, and equipment. Diagnostic flow varies by platform — see the matching breakdown:
Which Vehicles Commonly Get POWERSTROKE-P1391?
- 1994.5-1997 Ford F-250/F-350 7.3L Power Stroke
- 1999-2003 Ford F-250/F-350 Super Duty 7.3L Power Stroke
- 1999-2003 Ford F-450/F-550 Super Duty 7.3L Power Stroke
- 1994.5-2003 Ford E-350/E-450 7.3L Power Stroke
- 2000-2003 Ford Excursion 7.3L Power Stroke
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