Diesel Trouble Codes

P0380 — Glow Plug/Heater Circuit A — 6.0 Power Stroke

Diagnostic reference for P0380 on 6.0 Power Stroke (2003.5–2007).

Updated October 15, 2026

What it means

The PCM has detected an electrical fault in the glow plug heater circuit. On the 6.0L glow plugs are run by a frame-mounted glow plug control module (GPCM); check for per-cylinder glow plug codes, the GPCM and its power feed. Expect hard cold starts and white smoke.1

Most likely causes

  1. GPCM power/ground or connector corrosion — The GPCM sits on the frame rail and is exposed to moisture and road salt. Corrosion or loose terminals at the GPCM connector can interrupt the heater circuit command and set P0380.123
  2. Failed or intermittent GPCM — A failing GPCM can lose communication with the PCM or fail to drive the glow plugs, triggering a circuit A fault and often accompanying P0683.13
  3. Open/shorted wiring between PCM and GPCM — The PCM-to-GPCM command wire can chafe or corrode, causing the PCM to detect a circuit fault.2
  4. Multiple glow plug circuit faults masking as circuit A — Per-cylinder glow plug faults (P0671–P0678) can accompany a general circuit A fault when several plugs or the under-valve-cover harness are degraded.14

How to diagnose

  1. Verify freeze frame and related codes. Look for P0671–P0678, P0670, P0683 alongside P0380.
  2. Inspect GPCM power and ground feeds and connector for corrosion, moisture, or loose pins. The GPCM is frame-mounted and prone to water damage.
  3. Check PCM-to-GPCM wiring for chafing, corrosion, or opens; confirm continuity and isolation to ground/power.
  4. Command glow plug operation with a scan tool and monitor GPCM feedback/communication status; a loss of communication suggests GPCM failure or wiring fault.
  5. If per-cylinder codes are present, test individual glow plug resistance and inspect under-valve-cover harness/connectors for damage or oil intrusion.

Specs and test values

CheckNormal readingWhen to measureSource
Battery and charging voltage12.6–12.7 V at rest when fully charged; about 13.5 V runningEngine off, then running with loads onDieselHub
Glow plug resistanceLow — usually no more than about 6 Ω — and similar on every plug; an open reading means a failed plugEngine off, meter lead to engine groundDENSO

Common mistake to avoid

Replacing glow plugs or the glow module before checking the batteries. The glow system draws heavily, and low battery voltage causes circuit faults that no part swap will fix. Source: FleetRabbit — P0670 glow plug control module fault.

Parts and tools you may need

Tools you’ll need

Rough cost and difficulty

Likely repairPartsShop laborWho usually does it
ECM/PCM software update—0.5–1.5 hrsShop
Wiring or connector repair$10–$1001–4 hrsDIY with tools and a manual
Glow plugs (full set)$80–$2502–6 hrsDIY with tools and a manual
Glow plug relay or control module$60–$4000.5–2 hrsEasy DIY

Typical US independent-shop figures; labor runs about $120–$180 per hour (dealers charge more). Confirm the diagnosis before buying parts.

When to see a pro

Glow plug circuits are on the high-current side of the GPCM and under-valve-cover harnesses. If diagnosis points to internal harness faults or GPCM replacement, have a qualified diesel technician perform the work to avoid electrical damage or incorrect repairs.

Check for recalls

Recalls are tied to your truck’s VIN, so check yours directly: enter the VIN at NHTSA’s recall lookup. Open safety recalls are repaired free at a dealer.

Sources

  1. Curated DTC seed — 6.0 Power Stroke (curated) ↩︎ ↩︎ ↩︎ ↩︎

  2. Curated DTC seed — 6.0 Power Stroke (curated) ↩︎ ↩︎

  3. Curated DTC seed — 6.0 Power Stroke (curated) ↩︎ ↩︎

  4. Curated DTC seed — 6.0 Power Stroke (curated) ↩︎