P0673 on Chevrolet: How to Diagnose & Fix
Cylinder 3 Glow Plug Circuit
2 Chevrolet models · 2 documented issues · $200-$1,800 repair
P0673 on Chevrolet by model: symptoms, diagnosis and fix
Glow plugs fail causing difficult cold weather starting. Can also swell and break during removal, requiring extraction. Glow plug module can also fail.
Common Symptoms
- Hard starting in cold weather
- Extended cranking
- White smoke on cold start
- Glow plug indicator stays on too long
- Rough idle when cold
How to Fix
Replace failed glow plugs. Use penetrating oil and heat to prevent breakage during removal. Replace glow plug controller module if diagnostics indicate module failure.
Sources for this issue (1)
The 6.6L Duramax LGH offered in Express 2500/3500/4500 vans from 2011 to 2016 has a well-documented glow plug system weakness. Individual glow plugs fail open, and the glow plug control module itself develops open-driver and no-power-to-glow-plug faults - a failure mode common enough that specialist board-repair houses list the 2011-2016 Chevrolet Express 6.6L LGH GPCM as a standing repair line. GM issued a service bulletin covering 2011-2012 Express vans with the LGH and LML Duramax where the malfunction indicator lamp illuminates for glow plug faults; the bulletin notes there is usually no drivability complaint in mild weather, but harder cold starting may be present. In practice owners in cold climates get extended cranking, white startup smoke and a rough first minute of running, plus a persistent MIL that will fail an inspection. Do not confuse this with the 2017-2022 Express, which offered the completely different 2.8L Duramax four-cylinder; the diesel was dropped for 2023.
Common Symptoms
- Malfunction indicator lamp on with glow plug circuit codes
- Extended cranking in cold weather
- White smoke on cold startup
- Rough running for the first minute after a cold start
- Wait-to-start behavior that never satisfies
How to Fix
Scan for the specific glow plug circuit code to identify which cylinders report open, then load-test each glow plug individually - a single open plug sets the light, so replacing the module first is a common misdiagnosis. If the module reports open drivers or no output at all, the GPCM is at fault and can either be replaced new or sent for board-level repair at a fraction of dealer cost. When multiple plugs test bad, replace the full set; mixing old and new plugs invites a repeat visit. Access is tight - budget significant labor, particularly on the driver's side in the van body. No recall covers this. GM special coverage 15114 covered the glow plug on 2011-2012 Express vans for 10 years/120,000 miles, but that coverage has now expired by age.
Sources for this issue (4)
- GM Special Coverage Adjustment 15114 - MIL Lamp On / Glow Plug Heater Inoperative (2010-2012 Express/Savana 6.6L LML, LGH)tsb
- 2011-2016 Chevrolet Express 2500/3500/4500 6.6L Duramax LGH Glow Plug Control Module Repair - documented failure modes: no power to glow plugs, open driver errorsarticle
- $4,000 Duramax glow plug problem "not uncommon" per Chevrolet Customer Service - Chevy and GMC Duramax Diesel Forumforum
- Glow plugs going bad - Chevy and GMC Duramax Diesel Forumforum
P0673 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 P0673 mean on a Chevrolet?
P0673 stands for "Cylinder 3 Glow Plug Circuit." This is a diesel engine code. Glow plugs heat each cylinder's combustion chamber to make starting easier, particularly in cold conditions. P0673 means the glow plug control system detected an electrical problem in the cylinder 3 glow plug circuit — usually an open circuit, a short, or out-of-range resistance. You'll most likely notice harder cold starts, rough idle while warming up, or extra startup smoke; the glow plug warning light may also illuminate. On Chevrolet it is documented across 2 models: Silverado 3500HD, Express.
What are the most common causes of P0673?
The most common causes of P0673 are: Failed (open or shorted) cylinder 3 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 P0673 on a Chevrolet?
Published repair estimates on Chevrolet range from $200 to $1,800 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.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.