P0674 on Mercedes-Benz
Cylinder 4 Glow Plug Circuit
P0674 on Mercedes-Benz vehicles indicates cylinder 4 glow plug circuit. Au7o has documented this code across 1 Mercedes-Benz model — most commonly on Sprinter. This is a diesel engine code. Glow plugs preheat each cylinder so the diesel fuel ignites reliably, especially during cold starts. P0674 means the glow plug control system detected an electrical fault in the cylinder 4 glow plug circuit — commonly an open circuit, a short, or resistance outside the normal range. The typical symptoms are difficult cold starting, rough running until the engine warms, more startup smoke, and possibly an illuminated glow plug indicator. Typical repair costs on Mercedes-Benz range from $300 to $1,500, depending on the specific model and root cause.
Common Causes of P0674
- •Failed (open or shorted) cylinder 4 glow plug
- •Damaged or corroded glow plug wiring/connector
- •Loose or corroded glow plug terminal/strap
- •Faulty glow plug relay or control module
- •Broken or chafed harness to the glow plug
- •Poor ground or low supply voltage to the circuit
P0674 on Mercedes-Benz by Model
Mercedes-Benz Sprinter(1 issue)
- Glow Plug Failure and Cold Start Issues2007-2025
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.
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View P0674 across all makes →Frequently Asked Questions
What does P0674 mean on Mercedes-Benz?▼
P0674 stands for "Cylinder 4 Glow Plug Circuit." This is a diesel engine code. Glow plugs preheat each cylinder so the diesel fuel ignites reliably, especially during cold starts. P0674 means the glow plug control system detected an electrical fault in the cylinder 4 glow plug circuit — commonly an open circuit, a short, or resistance outside the normal range. The typical symptoms are difficult cold starting, rough running until the engine warms, more startup smoke, and possibly an illuminated glow plug indicator. On Mercedes-Benz specifically, this code is documented across 1 model.
What causes P0674 on Mercedes-Benz vehicles?▼
Common causes on Mercedes-Benz: Failed (open or shorted) cylinder 4 glow plug, Damaged or corroded glow plug wiring/connector, Loose or corroded glow plug terminal/strap, Faulty glow plug relay or control module, Broken or chafed harness to the glow plug. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0674 on a Mercedes-Benz?▼
Repair costs on Mercedes-Benz range from $300 to $1,500, depending on the specific model and root cause.
Which Mercedes-Benz models have P0674 documented?▼
Au7o has documented P0674 on 1 Mercedes-Benz model: Sprinter.