P0381Glow Plug/Heater Indicator Control Circuit/Open
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P0381 monitors the circuit of the wait-to-start lamp for an open circuit or, more generally, for faults that keep the lamp dark when commanded – CARB names a burnt-out bulb as the example, with exemptions for LCD clusters and for engines that only release the starter after preheating. GM's 2015–2018 diesels detect an open circuit in the driver by a high load impedance (about 200 kΩ in 2015), in 0.2 s or 10 of 15 samples, with the check engine light after two trips; on the 2014 Duramax LML P0381 still covered all lamp circuit faults including a short to ground. Ford's 2023 diesels check via the instrument cluster: if it reports the lamp off although on is commanded, P0381 is set within about 1 s at key-on. There is no limp mode; the risk is starting too early in the cold.
- What you may notice
- Glow plug light does not come on at key-on
- Check engine light on (GM after two trips)
- Driver starts too early in the cold
- Likely causes
- LikelyControl wire open or connector fault between engine module and cluster
- PossibleLamp or LED in the instrument cluster burnt out
- RareInstrument cluster faulty or communication problem (Ford)
- RareDriver in the engine module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €50 – €500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.