P0674: Cylinder 4 Glow Plug Circuit
3 vehicles · 3 makes · $200-$1,500 repair
Most Reported On
P0674 is an OBD-II diagnostic trouble code meaning “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. This code is most commonly reported on 2007-2025 Mercedes-Benz Sprinter (Sprinter 1500, Sprinter 2500, Sprinter 3500, Sprinter 4500), 2001-2020 Chevrolet Silverado 3500HD, and 2007-2019 GMC Sierra 3500HD, with repair costs ranging from $200 to $1,500.
Common Causes
Typical Repair Cost
Based on 3 documented vehicle-specific issues. Actual cost depends on root cause and vehicle.
Diagnostic Tools
To diagnose P0674, you'll need an OBD-II scanner. Here are our recommendations at every price point.
ANCEL AD310 Classic OBD-II Scanner
by ANCEL
A simple, affordable code reader that reads and clears check engine codes. Great for quick diagnostics on any OBD-II vehicle (1996+).
- Read & clear engine codes
- View freeze frame data
- I/M readiness status
- No batteries or app needed
BlueDriver Pro Bluetooth Scanner
by BlueDriver
Bluetooth OBD-II scanner with a free companion app. Provides enhanced diagnostics, smog readiness, and repair reports sourced from a database of verified fixes.
- Enhanced diagnostics (ABS, SRS, transmission)
- Repair Reports with verified fixes
- Smog check readiness
- Free app (iOS & Android)
LAUNCH CRP123X OBD-II Scanner
by LAUNCH
A professional-grade handheld scanner that reads all four major systems (engine, transmission, ABS, SRS) with live data streaming and graphing.
- Engine, transmission, ABS, SRS diagnostics
- Live data stream & graphing
- AutoVIN for vehicle identification
- Free lifetime updates via Wi-Fi
Autel MaxiCOM MK808S Diagnostic Tool
by Autel
Shop-level diagnostic tablet with bi-directional control, active tests, and full system coverage. Ideal for serious DIYers and small shops.
- All-system diagnostics (25+ modules)
- Bi-directional control & active tests
- Oil reset, EPB, BMS, TPMS, injector coding
- 7-inch touchscreen with Android OS
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Vehicles Affected (3)
FAQ
What does P0674 mean?
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.
What are the most common causes of P0674?
The most common causes of P0674 are: 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. The specific cause varies by vehicle.
How much does it cost to fix P0674?
Repair costs for P0674 range from $200 to $1,500, depending on the vehicle and root cause.
Which vehicles are affected by P0674?
Au7o has documented P0674 across 3 vehicle models from 3 manufacturers: Chevrolet, GMC, Mercedes-Benz.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.