Diesel Trouble Codes

P0380 — Glow Plug/Heater Circuit Malfunction (5.9 Cummins Common Rail)

P0380 is a generic OBD-II code for a glow-plug/heater circuit electrical fault detected by the ECM. On the 2003-2007 5.9L Cummins Common Rail this code does…

Updated September 2, 2026

What it means

The ECM has detected an electrical fault in a heater-type circuit. On this platform the engine uses an intake-air grid heater for cold start and has NO glow plugs. Therefore P0380 is not applicable to the 5.9L Cummins Common Rail hardware as defined; the code is a generic mismatch for this engine family.12

Most likely causes

  1. Code mis-match / generic definition not supported by platform hardware — The platform facts state Cold start: intake-air grid heater. NO glow plugs. The generic P0380 definition refers to a glow plug heater circuit, which this engine does not have.12
  2. ECM/PCM software or scan-tool misinterpretation — A generic OBD-II reader may report P0380 on a platform where no glow-plug circuit exists, leading to a false positive. The authoritative platform facts confirm no glow plugs are fitted.12
  3. Wiring harness / connector issue causing ECM to see an unexpected heater circuit fault — Although the engine has no glow plugs, the ECM monitors heater-type circuits such as the intake grid heater. An open/short in related heater wiring can trigger a generic heater-circuit DTC on some tools. Platform facts confirm grid heater presence and no glow plugs.12

How to diagnose

  1. Verify platform and code applicability: confirm vehicle is 2003-2007 Dodge Ram 2500/3500 ISB 5.9 Common Rail with intake grid heater and no glow plugs.
  2. Check scan tool data and code definition source; confirm P0380 is being reported as generic glow plug/heater circuit malfunction.
  3. Inspect ECM freeze frame and related heater circuit monitors; look for grid heater relay, intake air heater, or other heater-type circuits that could be mis-identified. Platform facts: cold start uses grid heater, no glow plugs.
  4. Inspect wiring and connectors for the intake grid heater circuit for opens, shorts, or high resistance; verify relay and fuse condition. Platform facts confirm grid heater exists.
  5. If no actual heater circuit fault is found and engine starts/ runs normally in cold conditions, treat P0380 as non-applicable to this platform and clear the code; monitor for reoccurrence with a Cummins-specific scan tool.

Parts and tools you may need

Rough cost and difficulty

Diagnostic time only; no glow-plug parts exist on this platform. If a grid heater circuit repair is needed, cost varies by relay, wiring, or heater element.

When to see a pro

If the code persists with a Cummins-specific tool, or if cold-start performance is poor, have a diesel technician verify grid heater operation and ECM calibration. Do not attempt high-pressure fuel system service for this code.

Sources

  1. Curated DTC seed — 5.9 Cummins Common Rail (curated) ↩︎ ↩︎ ↩︎ ↩︎

  2. Curated DTC seed — 5.9 Cummins Common Rail (curated) ↩︎ ↩︎ ↩︎ ↩︎