P0380 on Mercedes-Benz: How to Diagnose & Fix
Glow Plug/Heater Circuit A Malfunction
1 Mercedes-Benz model · 1 documented issue · $300-$1,500 repair
P0380 on Mercedes-Benz by model: symptoms, diagnosis and fix
Sprinter glow plugs fail with age, causing hard starting in cold weather, rough idle when cold, and white smoke on startup. The OM642 V6 is particularly prone to glow plug seizure in the cylinder head, making removal difficult and risking broken glow plugs that require cylinder head removal to extract.
Common Symptoms
- Hard starting in cold weather
- Extended cranking before engine fires
- Rough idle for first 30-60 seconds when cold
- White smoke on startup
- Glow plug warning light staying on
How to Fix
Replace all glow plugs as a set. Apply anti-seize compound to new glow plug threads. On the OM642, use penetrating oil on the glow plugs and allow it to soak before removal to reduce seizure risk. If a glow plug breaks during removal, specialized extraction tools are available before resorting to head removal.
Owner tips & cautions
- TipReplace glow plugs proactively every 80,000 miles before they seize. Apply anti-seize compound generously. A broken glow plug extraction on the OM642 can cost $1,000+ in labor alone.
P0380 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0380 mean on a Mercedes-Benz?
P0380 stands for "Glow Plug/Heater Circuit A Malfunction." P0380 applies to diesel engines and means the computer detected a malfunction in glow plug heater circuit 'A'. Glow plugs preheat the combustion chambers to help a cold diesel start, and the control module monitors the glow plug circuit (often through a relay/control module); when the current or voltage isn't what it expects, it sets this code. The most noticeable symptom is hard cold starting, rough running until warm, or extra white smoke at startup. It indicates an electrical fault in the glow plug system rather than a fuel-injection problem. On Mercedes-Benz it is documented across 1 model: Sprinter.
What are the most common causes of P0380?
The most common causes of P0380 are: One or more failed glow plugs, Faulty glow plug control module or relay, Corroded or loose glow plug wiring/connectors, Open or shorted glow plug circuit wiring, Blown glow plug fuse, Poor power feed or ground to the glow plug circuit, Failed driver in the engine control module. The specific cause varies by vehicle.
How much does it cost to fix P0380 on a Mercedes-Benz?
Published repair estimates on Mercedes-Benz range from $300 to $1,500 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0380 on a different make?
View P0380 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.