OBD-II Code
P0672
Severity
Not yet reviewed
Nobody on our side has assessed this code yet, so we are not going to guess at how serious it is.
Can you drive it
We cannot say
Treat it as unknown until a shop reads it with live data. If the check-engine light is FLASHING, stop driving as soon as it is safe to — that means an active misfire, whatever the code.
Indicative cost (USD)
$80–$1,400
From this code's diagnostic notes. Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
$80 (single plug DIY) to $1,400 (full set of 6-8 plugs plus GPCM).
P0672 means the ECU detected a fault in the glow plug circuit feeding cylinder 1 specifically — typically an open circuit, a short to ground, or a resistance reading outside spec.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then follow the diagnostic notes further down this page, in the order they are written.
They are written in the order a shop works this code, cheapest checks first. Where they name a component, inspect its wiring and connector before replacing it.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Check engine light
Read the full diagnostic procedureP0672 means the ECU detected a fault in the glow plug circuit feeding cylinder 1 specifically — typically an open circuit, a short to ground, or a re…
P0672 means the ECU detected a fault in the glow plug circuit feeding cylinder 1 specifically — typically an open circuit, a short to ground, or a resistance reading outside spec. Glow plugs are heating elements that pre-warm the combustion chamber on a diesel for cold starts, and the Glow Plug Control Module (GPCM) monitors each cylinder's circuit individually for current draw during the glow-on cycle.
The cheapest-first diagnostic ladder
- Pull the glow plug harness connector at cylinder 1 and ohm the plug at its terminal — a healthy glow plug measures 0.4-2.0 ohms cold (most diesels land 0.6-1.2 ohms); below 0.3 ohms is shorted internally, infinite/OL is open/burned out, and 4+ ohms is a marginally weak plug that's the most common cold-start hard-start root cause.
- Back-probe the harness side and confirm the GPCM is sending the commanded PWM signal — 0-100% duty cycle depending on coolant temp, with glow-on time typically 5-30 sec (longer below 20F, shorter above 60F).
- Clamp an inductive amp probe over the cylinder 1 glow plug feed wire and watch current during the glow cycle — healthy plugs draw 7-20A initial inrush that falls to 5-15A as the element heats and resistance rises. A flat 0A reading with the GPCM commanding ON is an open circuit between the module and the plug (broken wire, bad connector pin, or burned-out plug). Test resistance INDIVIDUALLY at the glow plug terminal — pulling a shorted plug measures 0 ohms; an open plug measures infinite; a marginally weak plug measures 4+ ohms cold and is the most common cold-start hard-start root cause. Replace as a set on diesel engines — mixed-age plugs cause progressive failure.
Vehicle-specific patterns2003-2007 Ford 6.0L Powerstroke commonly throws P0672 from harness chafing where the glow plug pigtail crosses the valve cover — cylinder 1 sits at t…
- 2003-2007Ford 6.0L Powerstroke commonly throws P0672 from harness chafing where the glow plug pigtail crosses the valve cover — cylinder 1 sits at the front driver's side and sees the most heat-cycle stress; the fix is the updated International harness with sleeving plus a new plug.
- 2001-2010Duramax LB7/LLY/LBZ/LMM frequently throws P0672 when the GPCM's cylinder 1 driver fails — Duramax cyl 1-7 are on the driver's bank (left front), and the GPCM lives on the passenger inner fender where it cooks in summer heat; replace the plug AND the module if amp draw is zero at the plug pigtail.
- 2007-2018Dodge/RAM Cummins 6.7 inline-6 throws P0672 from the well-known glow plug harness connector corrosion at cylinder 1 (front of the head, closest to the radiator overspray); dielectric grease and a fresh OEM connector resolves it.
- 2007-2018Mercedes Sprinter OM642 3.0L V6 BlueTec commonly throws P0672 from a single weak plug among six — Mercedes specs all six replaced together because mixed-age plugs cascade-fail within 6 months.
Estimated repair$80 (single plug DIY) to $1,400 (full set of 6-8 plugs plus GPCM).
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