P0380
Glow Plug/Heater Circuit "A" Malfunction
The glow plug control module reports an electrical fault on circuit A — typically a single glow plug open-circuit, the relay failing, or wiring to the harness damaged. Diesel-specific; affects cold-start behaviour.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
Symptoms
- Glow plug warning light on (often orange coil symbol)
- Hard cold start or no start in cold weather
- White smoke from exhaust during warm-up
Common causes
Ordered by how often each turns out to be the cause.
- One or more glow plugs open-circuitCommon
- Glow plug relay failedPossible
- Wiring/harness damageLess likely
Parts involved
- Glow Plug
- Glow Plug Relay
- Glow Plug Control Module
P0380 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.