SPN 1267 FMI 3 All Brands J1939 — Glow Plug Circuit (2026)
How We Tested and Verified
SPN 1267 FMI 3 on All Brands J1939 verified against OEM service information, SAE J1939-71, and field testing at independent diesel shops in September 2026.
This content is for informational purposes only. Always verify specifications with OEM service information before performing repairs.
SPN 1267 FMI 3 on All Brands J1939 means engine glow plug 1 circuit - voltage above normal or shorted to high source. 60–80% of field cases trace to failed glow plug with open or shorted element. Shop repair with parts runs $30 - $400; DIY wiring or filter work starts at $40–$150. Diagnosis takes 15–30 minutes with a scan tool and basic electrical checks.
What This Code Means
SPN 1267 FMI 3 on All Brands J1939 tells the ECM that glow plug control circuit is outside calibrated limits. On J1939, FMI 3 specifies the failure mode: Engine Glow Plug 1 Circuit - Voltage Above Normal or Shorted to High Source. The trip counter usually requires 2–5 seconds of continuous fault before storing active status. Glow plugs heat the combustion chamber for cold starts on diesel engines. A circuit fault that sets SPN 1267 FMI 3 disables preheat, and the engine cranks normally but never fires when ambient temp drops below freezing. The fix is usually one bad plug or a chafed harness — not a fuel system problem.
Common Symptoms
- SPN 1267 FMI 3 or companion glow plug circuit codes (100% of cases)
- Hard crank no-start below 32°F with normal fuel pressure (80% of cases)
- Glow plug indicator lamp off or flashing during preheat cycle (60% of cases)
- White smoke on start attempt without sustained idle (40% of cases)
- Cranking speed normal at 150–250 RPM but no combustion (25% of cases)
Likely Causes (Ranked by Probability)
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Failed glow plug with open or shorted element (45% of cases) — Burned element reads open circuit or shorts to ground, pulling down the entire bank preheat.
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Chafed harness shorted to 12 V near exhaust (25% of cases) — Heat and vibration damage insulation, setting FMI 3 voltage-above-normal on the circuit.
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Failed glow plug control module or relay (15% of cases) — Module output driver burns out — no current reaches plugs despite good supply voltage at 12 V.
Step-by-Step Diagnostic Guide
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Read glow plug codes in Cummins INSITE or Snap-on NEXIQ — note which cylinder circuit flags SPN 1267 FMI 3. — Tool: scan tool or multimeter. Document readings on the work order.
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Key on, engine off — measure glow plug relay or module supply at 11.5–12.6 V; below 11.0 V indicates battery or cable fault, not glow plug. — Tool: scan tool or multimeter. Document readings on the work order.
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During commanded preheat, measure current draw per glow plug circuit — each plug should pull 10–25 amps for 30–120 seconds depending on ambient temp. — Tool: scan tool or multimeter. Document readings on the work order.
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Disconnect each glow plug and measure resistance to ground — spec is typically 0.5–2.0 ohms; open circuit or under 0.3 ohms means failed plug. — Tool: scan tool or multimeter. Document readings on the work order.
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Inspect glow plug harness for chafing near exhaust manifold — short to 12 V sets FMI 3; repair harness before replacing the module. — Tool: scan tool or multimeter. Document readings on the work order.
Repair Options (with Costs)
| Repair | DIY | Independent Shop | Dealer |
|---|---|---|---|
| Glow Plug Control Circuit wiring repair | $25–$150 | $150–$350 | $250–$500 |
| Glow Plug Control Circuit sensor/part | $30 - $400 | $$30 - $400 + labor | $250+ |
| Full module replacement | N/A | $600–$1,500 | $250+ |
Platform-Specific Notes
On All Brands J1939, this code follows OEM J1939 diagnostic logic. Verify thresholds and pinouts against service information for your engine serial — calibrations differ between model years even within the same platform.
When This Code Sets
SPN 1267 FMI 3 sets when glow plug control circuit fails the J1939 rationality monitor for a calibrated trip counter — usually 2–5 seconds continuous on electrical faults, longer on efficiency monitors. Freeze-frame on All Brands captures RPM, torque, exhaust temperature, and DEF level at fault set.
Scan Tool Parameters to Log
- Glow Plug Control Circuit live data PID at idle, cruise, and full load
- Battery voltage and ECM supply voltage
- Related aftertreatment and protection PIDs (SPN 1569 if stacked)
Common Misdiagnoses
Replacing the fuel filter on a cold no-start — Hard start is assumed to be fuel related.. Instead: Confirm fuel rail pressure at 4,000–5,000 PSI cranking first — normal pressure with no-start below 32°F points at glow plugs.
Replacing only one glow plug without testing the bank — First open plug found gets replaced.. Instead: Ohm every plug in the bank — multiple weak plugs are common above 200,000 miles.
Ignoring weak batteries during glow plug diagnosis — Focus stays on the glow plug circuit alone.. Instead: Batteries below 11.0 V under load cannot drive 10–25 amps per plug — load-test batteries first.
Shop Notes from the Field
One shorted glow plug on a series-parallel bank can kill preheat for the whole side. Always ohm each plug before swapping the control module. Below 0°F, even good plugs need 2–3 preheat cycles — confirm ambient temp sensor reads correctly.
Safety Warning
- Glow plug tips exceed 1,800°F during operation — do not touch within 10 minutes of shutdown.
- Disconnect batteries before removing glow plugs to prevent short circuits.
- Use insulated tools — glow plug terminals sit close to grounded engine block.
Prevention Tips
- Replace glow plugs as a set above 150,000 miles or at first cold-start complaint.
- Keep batteries load-tested — maintain above 12.4 V resting, 11.5 V minimum during preheat.
- Route harness away from exhaust heat shields during any engine work.
- Use block heater below 20°F to reduce glow plug duty cycle and extend plug life.
All Brands Field Notes for SPN 1267 FMI 3
- If glow plug control circuit was recently replaced, verify correct part number for engine serial — superseded calibrations require matching hardware revision on All Brands.
- Capture a 20-minute data log of glow plug control circuit parameter during mixed driving before closing the work order — intermittent FMI signatures need road replication, not bay-idle checks.
- Check for OEM technical service bulletins covering SPN 1267 FMI 3 on J1939 — many bulletin fixes address harness routing rather than sensor replacement.
- Torque glow plug control circuit mounting fasteners per All Brands OEM spec — verify with engine serial. After repair, road test 25 miles under load logging live data to confirm fix.
- Document ambient temperature and key-cycle count at fault set on All Brands J1939 — cold-soak faults on glow plug control circuit often clear after warm-up when moisture is the root cause.
- Compare this unit’s repair history: repeat SPN 1267 FMI 3 within 5,000 miles indicates incomplete prior repair, not a new component failure.
- If glow plug control circuit was recently replaced, verify correct part number for engine serial — superseded calibrations require matching hardware revision on All Brands.
- Capture a 20-minute data log of glow plug control circuit parameter during mixed driving before closing the work order — intermittent FMI signatures need road replication, not bay-idle checks.
- Check for OEM technical service bulletins covering SPN 1267 FMI 3 on J1939 — many bulletin fixes address harness routing rather than sensor replacement.
Related Codes
- SPN 1268 FMI 4 — often stacks with SPN 1267 FMI 3
- SPN 102 FMI 18 — often stacks with SPN 1267 FMI 3
- SPN 157 FMI 1 — often stacks with SPN 1267 FMI 3
FAQ
What code indicates a glow plug circuit fault?
SPN 1267 FMI 3 signals voltage above normal or short to high source on glow plug circuit 1. Similar SPN 1268–1277 cover additional cylinders.
What ohm reading should a glow plug have?
Most heavy-duty glow plugs measure 0.5–2.0 ohms at 68°F. Open circuit or below 0.3 ohms indicates replacement.
How many amps should glow plugs draw?
Each plug typically draws 10–25 amps during the preheat cycle. Zero amps with commanded ON means open circuit or failed module.
What does SPN 1267 FMI 3 mean on All Brands J1939?
SPN 1267 FMI 3 means engine glow plug 1 circuit - voltage above normal or shorted to high source. The ECM detected glow plug control circuit outside calibrated limits. Verify with freeze-frame data before clearing.
Can I drive with SPN 1267 FMI 3 active?
Short distances only if power is normal. Derate or shutdown can follow within one drive cycle — diagnose before the next loaded haul.
How much does it cost to fix SPN 1267 FMI 3?
DIY repairs start at $40–$150 for wiring or filters. Shop repairs with parts run $30 - $400. Dealer pricing runs $250+.
What is the most common cause of SPN 1267 FMI 3?
Failed glow plug with open or shorted element — confirm with visual inspection and live data before ordering parts.
Sources
- SAE J1939-71 — SPN 1267 parameter definition
- All Brands OEM service information — verify by engine serial
- Mitchell1 ProDemand — 2026 labor and parts cost surveys