Glow Plug/Heater Indicator Circuit
The P0381 code means the vehicle's onboard diagnostic system has detected: Glow Plug/Heater Indicator Circuit. This is a low severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- easy
- Estimated cost
- $20 - $200 (parts and labor)
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Common Symptoms
- Glow plug indicator light does not work
- Check Engine Light may be on
- No wait-to-start light on dashboard
- Engine starts normally
Probable Causes (Ranked by Likelihood)
- Burned-out glow plug indicator bulb Very High
- Faulty glow plug control module not sending indicator signal High
- Damaged wiring to instrument cluster Moderate
- Instrument cluster fault Low
Frequently Asked Questions
Is P0381 a serious code?
No, P0381 only affects the dashboard indicator light. The glow plugs themselves may be functioning normally.
Do I still need to wait for the glow plug light?
Even if the light is not working, the glow plugs still operate normally. In very cold weather, wait 5-10 seconds before cranking to allow them to heat.
Can I pass emissions with P0381?
The Check Engine Light may cause an emissions test failure, but the code itself is not emissions-critical.
Mechanics Guide Step-by-step diagnosis
Step-by-Step Diagnostic Procedure
-
Check if the glow plug indicator light illuminates during bulb check (key on, engine off).
-
Test the indicator light circuit with a test light.
-
Check glow plug control module output for the indicator signal.
-
Inspect wiring between control module and instrument cluster.
Sources 2
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
- Cross-checked against the SAE J2012:2002 DTC table (2026-08-27)archived scan of the SAE standard — readable copy, not SAE’s current edition
P0381 on Diesel, EV & Equipment
The same code ID appears across other engines and platforms. The diagnostic flow varies by manufacturer — these are the platform-specific breakdowns:
Commonly Affected Vehicles
- 2010-2020 Ford F-250 (6.7L Diesel)
- 2012-2019 Ram 2500 (6.7L Cummins)
- 2008-2018 Chevrolet Silverado 2500 (6.6L Duramax)
- 2011-2020 GMC Sierra 2500 (6.6L Duramax)
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