P0672 on Mercedes-Benz: How to Diagnose & Fix
Cylinder 2 Glow Plug Circuit
1 Mercedes-Benz model · 1 documented issue · $300-$1,500 repair
P0672 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.
P0672 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 P0672 mean on a Mercedes-Benz?
P0672 stands for "Cylinder 2 Glow Plug Circuit." P0672 is a diesel-engine code indicating a fault in the glow plug circuit for cylinder number 2. Glow plugs heat the combustion chamber to help a diesel engine start, especially in cold weather, and the control module monitors each plug's circuit electrically. When it detects an open, short, or out-of-range condition on the cylinder 2 glow plug circuit, it sets this code. It generally causes hard cold starts, rough running until warm, and possibly white smoke on startup, while the check engine or glow plug light may illuminate. On Mercedes-Benz it is documented across 1 model: Sprinter.
What are the most common causes of P0672?
The most common causes of P0672 are: Failed (open or shorted) glow plug on cylinder 2, Corroded or loose glow plug connector/terminal, Damaged or broken glow plug wiring/harness, Faulty glow plug control module or relay, High resistance/corrosion at the glow plug bus bar or strap, Poor ground connection in the glow plug circuit, Blown fuse feeding the glow plug circuit. The specific cause varies by vehicle.
How much does it cost to fix P0672 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 P0672 on a different make?
View P0672 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.