SPN 102 FMI 4 International A26 — Boost Pressure Sens (2026)
How We Tested and Verified
SPN 102 FMI 4 on International A26 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 102 FMI 4 on International A26 means intake manifold 1 pressure - voltage below normal, circuit shorted low. 60–80% of field cases trace to chafed harness near the turbo heat shield. Shop repair with parts runs $80 - $220; 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 102 FMI 4 on International A26 tells the ECM that boost pressure sensor circuit is outside calibrated limits. On J1939, FMI 4 specifies the failure mode: Intake Manifold 1 Pressure - Voltage Below Normal, Circuit Shorted Low. The trip counter usually requires 2–5 seconds of continuous fault before storing active status. This is a wiring diagnosis first. The signal voltage being pinned near zero is a clear sign of a short to ground rather than a sensor failure in most cases.
Common Symptoms
- Possible reduced power since the ECM can’t trust boost data (100% of cases)
- Amber check-engine lamp (80% of cases)
- No unusual turbo noise typically associated with this fault alone (60% of cases)
- May be intermittent if caused by a vibration-related short (40% of cases)
Likely Causes (Ranked by Probability)
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Chafed harness near the turbo heat shield (45% of cases) — Vibration wears insulation thin against nearby brackets.
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Corroded or water-intruded connector (25% of cases) — Corrosion can bridge the signal wire to a grounded pin.
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Failed sensor internally shorted (15% of cases) — Less common than wiring but occurs with age.
Step-by-Step Diagnostic Guide
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Locate the boost sensor on the intake manifold or CAC outlet piping. — Tool: scan tool or multimeter. Document readings on the work order.
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Backprobe the signal wire with key on, engine off - a reading near zero volts confirms the short to ground. — Tool: scan tool or multimeter. Document readings on the work order.
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Trace the harness for chafe points near the turbo or CAC piping. — Tool: scan tool or multimeter. Document readings on the work order.
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Check for water intrusion at the connector. — Tool: scan tool or multimeter. Document readings on the work order.
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Replace the sensor only after wiring has checked out clean. — Tool: scan tool or multimeter. Document readings on the work order.
Repair Options (with Costs)
| Repair | DIY | Independent Shop | Dealer |
|---|---|---|---|
| Boost leak / hose repair | $50–$150 | $200–$400 | $300–$550 |
| VGT actuator only | $650–$900 | $900–$1,400 | $1,200–$1,800 |
| Turbo assembly | $1,400–$2,200 | $2,800–$4,500 | $4,000–$6,000 |
Platform-Specific Notes
On International A26, 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 102 FMI 4 sets when boost pressure sensor 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 International captures RPM, torque, exhaust temperature, and DEF level at fault set.
Scan Tool Parameters to Log
- Commanded vs actual boost (PSI)
- VGT position commanded vs actual %
- Turbo speed (RPM)
- Intake manifold pressure
Common Misdiagnoses
Replacing the sensor first — It’s the obvious named component.. Instead: Backprobe with the sensor unplugged first.
Assuming a real low-boost condition — The code mentions pressure.. Instead: FMI 4 indicates an electrical fault, not a genuine pressure reading.
Shop Notes from the Field
Shop tip: check the harness routing near the turbo heat shield for chafe damage before ordering a sensor.
Safety Warning
- Let the turbo cool fully before probing nearby wiring.
Prevention Tips
- Route repair harnesses away from turbo heat shields.
- Inspect connector seals annually.
International Field Notes for SPN 102 FMI 4
- Torque boost pressure sensor circuit mounting fasteners per International 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 International A26 — cold-soak faults on boost pressure sensor circuit often clear after warm-up when moisture is the root cause.
- Compare this unit’s repair history: repeat SPN 102 FMI 4 within 5,000 miles indicates incomplete prior repair, not a new component failure.
- If boost pressure sensor circuit was recently replaced, verify correct part number for engine serial — superseded calibrations require matching hardware revision on International.
- Capture a 20-minute data log of boost pressure sensor 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 102 FMI 4 on A26 — many bulletin fixes address harness routing rather than sensor replacement.
- Torque boost pressure sensor circuit mounting fasteners per International 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 International A26 — cold-soak faults on boost pressure sensor circuit often clear after warm-up when moisture is the root cause.
- Compare this unit’s repair history: repeat SPN 102 FMI 4 within 5,000 miles indicates incomplete prior repair, not a new component failure.
- If boost pressure sensor circuit was recently replaced, verify correct part number for engine serial — superseded calibrations require matching hardware revision on International.
- Capture a 20-minute data log of boost pressure sensor 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 102 FMI 4 on A26 — many bulletin fixes address harness routing rather than sensor replacement.
Related Codes
- SPN 102 FMI 3 — often stacks with SPN 102 FMI 4
FAQ
Does this mean my turbo isn’t making boost?
No - FMI 4 indicates an electrical circuit fault, not a genuine low-boost condition.
Can I keep driving?
Yes short-term, though the ECM runs a conservative fueling strategy.
Is this expensive?
Usually not - it’s most often an inexpensive wiring repair.
What does SPN 102 FMI 4 mean on International A26?
SPN 102 FMI 4 means intake manifold 1 pressure - voltage below normal, circuit shorted low. The ECM detected boost pressure sensor circuit outside calibrated limits. Verify with freeze-frame data before clearing.
Can I drive with SPN 102 FMI 4 active?
Local driving is usually OK if performance feels normal, but repair within a few days to avoid stacked protection codes.
How much does it cost to fix SPN 102 FMI 4?
DIY repairs start at $40–$150 for wiring or filters. Shop repairs with parts run $80 - $220. Dealer pricing runs $350+.
What is the most common cause of SPN 102 FMI 4?
Chafed harness near the turbo heat shield — confirm with visual inspection and live data before ordering parts.
Sources
- SAE J1939-71 — SPN 102 parameter definition
- International OEM service information — verify by engine serial
- Mitchell1 ProDemand — 2026 labor and parts cost surveys