P0380: Glow Plug / Heater Circuit "A" Malfunction

P0380 is a diesel-only code meaning the engine control unit detected a fault in glow plug heater circuit "A" (the main glow plug circuit or its control relay). Glow plugs preheat the combustion chambers so a cold diesel can ignite. The ECU monitors the circuit for open or shorted wiring and a failed glow plug relay or module. Repairs typically run 60-400 EUR depending on whether a relay, wiring, or full plug set is needed.

P0380 is a electrical-related diagnostic trouble code classified as low severity. When your vehicle's ECU detects this condition, it stores P0380 and illuminates the check engine light.

If your vehicle has triggered P0380, you may notice one or more of these symptoms:

• Check engine light or glow plug indicator illuminated
• Hard or extended cranking when starting cold
• White or grey smoke from the exhaust on cold start
• Rough idle and misfire for the first minute after a cold start
• Reduced cold-weather startability, worse as temperatures drop
• Will likely fail a diesel emissions or technical inspection

Here are the most common causes of P0380, ranked by how likely they are to be the culprit:

Generally yes, for short-term driving. Safe to drive once the engine is warm. The glow plug system only assists cold starting on diesel engines, so the engine runs normally after warmup. Expect harder, longer cranking on cold mornings and more white smoke at startup. The car will likely fail a diesel inspection with this code stored.

Follow these steps to pinpoint the root cause of P0380:

1. Read the stored code and freeze frame with Skanyx or any ELM327 adapter to confirm P0380 and note the temperature at which it set
2. Check the glow plug system fuse and relay first, as a blown fuse or failed relay sets this circuit-level code
3. With the ignition off and glow plugs disconnected, bench-test each plug with a multimeter: a healthy glow plug reads roughly 0.5-2 ohm, while an open (infinite) reading means that plug has failed
4. Inspect the glow plug harness and connectors for corrosion, broken pins, or chafed wiring
5. Verify the relay/control module sends battery voltage to the plugs during the preheat cycle with a multimeter on the supply side
6. Note that per-cylinder glow plug live status is manufacturer-extended (Mode $22) data and is not available over generic OBD2, so the multimeter bench test is how you find the specific failed plug

Repair costs for P0380 vary depending on the root cause and your vehicle. Here are typical estimates:

P0380 behaves differently depending on your vehicle. Select your car below for model-specific causes, known issues, and adjusted cost estimates:

These codes are often seen alongside P0380 or indicate related issues: