P0672 on GMC
Cylinder 2 Glow Plug Circuit
P0672 on GMC vehicles indicates cylinder 2 glow plug circuit. Au7o has documented this code across 1 GMC model — most commonly on Sierra 3500HD. 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. Typical repair costs on GMC range from $250 to $1,200, depending on the specific model and root cause.
Common Causes of P0672
- •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
P0672 on GMC by Model
GMC Sierra 3500HD(1 issue)
- Glow plug control module / glow plug circuit faults causing hard cold starts (Duramax)2007-2019
Duramax-equipped Sierra 3500HD owners report hard starting, extended cranking, and rough idle in cold weather due to glow plug system faults. NHTSA complaints and service information commonly involve failed glow plugs, glow plug control module issues, or wiring/connector problems that trigger circuit DTCs and reduce preheat performance.
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View P0672 across all makes →Frequently Asked Questions
What does P0672 mean on GMC?▼
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 GMC specifically, this code is documented across 1 model.
What causes P0672 on GMC vehicles?▼
Common causes on GMC: 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. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0672 on a GMC?▼
Repair costs on GMC range from $250 to $1,200, depending on the specific model and root cause.
Which GMC models have P0672 documented?▼
Au7o has documented P0672 on 1 GMC model: Sierra 3500HD.