Cylinder 2 Glow Plug Circuit
The DURAMAX-P0672 (Duramax) diesel fault code means: Cylinder 2 Glow Plug Circuit. This is a moderate severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- intermediate
- Estimated cost
- $30-$80 per glow plug + labor; full set $250-$600
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Common Symptoms
- Hard start in cold weather
- White smoke at start-up
- Rough idle until warm
- Check Engine Light (may take one cold start to set)
Probable Causes (Ranked by Likelihood)
- Failed glow plug on cylinder 2 Very Likely
- Glow plug controller / relay fault Likely
- Broken glow plug tip — requires head removal (LLY/LBZ had 'swelled' glow plug failures) Possible
- Open or damaged glow plug wire Possible
Step-by-Step Diagnostic Procedure
Measure resistance across each glow plug — should be ~0.5-2 ohms, open = failed
Command glow plug 'on' with scan tool and verify battery voltage at the plug tip
Pull failed glow plug slowly — if it's swelled / broken, professional extraction may be required
Replace glow plug with OEM or Motorcraft-equivalent; torque to 18 ft-lb
Monitor for return after one or two cold starts to confirm repair
Frequently Asked Questions
What is P0672 on a Duramax?
Duramax code P0672 (Cylinder 2 Glow Plug Circuit) is a moderate-severity diagnostic trouble code triggered by the engine control module when it detects a problem in the associated system. On LLY/LBZ engines, glow plugs can swell and break inside the head — always unscrew them slowly while monitoring torque.
Is a Duramax P0672 safe to drive?
Yes in warm weather. In cold weather, a failed glow plug makes cold starts difficult and increases engine wear.
How much does it cost to fix P0672 on a Duramax?
Individual glow plug replacement is $30-$80 parts, 1-2 hours labor. Many owners replace all 8 if multiple are failing.
P0672 on Other Platforms
The same code ID appears across other engines, vehicles, and equipment. Diagnostic flow varies by platform — see the matching breakdown: