HighA26

SPN 3480 FMI 1 International A26 — HC Doser Fuel Supp (2026)

SPN 3480 FMI 1 on International A26 means hc doser fuel supply pressure - data valid but below normal operational range - moderately severe level. 60–80% of field cases trace to clogged hc doser fuel filter or restricted supply line. Shop repair with parts runs $150 - $850; 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 3480 FMI 1 on International A26 tells the ECM that hc doser fuel supply pressure is outside calibrated limits. On J1939, FMI 1 specifies the failure mode: HC Doser Fuel Supply Pressure - Data Valid But Below Normal Operational Range - Moderately Severe Level. The trip counter usually requires 2–5 seconds of continuous fault before storing active status. International LT and RH Series trucks set SPN 3480 FMI 1 when regen fuel pressure cannot support the seven-point doser spray pattern. ProfessionalDieselRepair.com ties this code to clogged doser fuel filters and weak supply pumps more often than failed doser valves.

Common Symptoms

• Check engine and HEST lamps with failed or aborted stationary regen events (100% of cases)
• SPN 3480 pressure reading below OEM minimum—often under 350 kPa on A26—in ServiceMaxx (80% of cases)
• Increasing DPF soot load percentage with SPN 4094 companion codes (60% of cases)
• White smoke or fuel smell near the doser valve during regen attempts (40% of cases)
• Progressive derate when regen cannot complete multiple times (25% of cases)

Likely Causes (Ranked by Probability)

1. Clogged HC doser fuel filter or restricted supply line (45% of cases) — Low flow at the doser pump drops supply pressure below the moderately severe threshold during regen.

2. Weak HC doser supply pump (25% of cases) — Worn pump internals cannot maintain 400+ kPa when the doser valve opens during active regen.

3. Air ingestion at doser fuel line fittings (15% of cases) — Loose banjo bolts or cracked hoses introduce air that collapses pressure spikes the ECM monitors.

Step-by-Step Diagnostic Guide

1. Connect ServiceMaxx or Noregon JPRO and read SPN 3480 live pressure during a commanded regen attempt. — Tool: scan tool or multimeter. Document readings on the work order.

2. Verify the HC doser fuel supply pump fuse and relay, then measure supply voltage at the pump: 12.4-14.2 V during crank and regen command. — Tool: scan tool or multimeter. Document readings on the work order.

3. Inspect the doser fuel filter and replace if differential pressure exceeds 15 psi; prime until ServiceMaxx shows stable supply above 400 kPa. — Tool: scan tool or multimeter. Document readings on the work order.

4. Check for leaking doser fuel lines at the metering pump and one-way check valve—air ingestion drops pressure below FMI 1 limits. — Tool: scan tool or multimeter. Document readings on the work order.

5. If mechanical pressure at the test port stays low with a new filter, test pump output flow at 0.3-0.5 L/min spec and replace the HC supply pump module if below minimum. — Tool: scan tool or multimeter. Document readings on the work order.

Repair Options (with Costs)

Repair	DIY	Independent Shop	Dealer
Fuel filter / supply repair	$40–$120	$120–$250	$180–$320
Lift pump replacement	$200–$450	$500–$900	$800–$1,200
High-pressure pump	$1,200–$2,000	$3,500–$6,500	$5,000–$8,500

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 3480 FMI 1 sets when hc doser fuel supply pressure 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 rail pressure (psi)
• Fuel supply pressure at HPFP inlet (8–12 psi target)
• Injector balance rates / contribution
• Fuel temperature and volume

Common Misdiagnoses

Replacing the DEF pump or SCR injector — Technicians assume all aftertreatment fluids share one pump.. Instead: Confirm SPN 3480 on the regen fuel circuit—parts-cannon DEF parts never fix HC doser pressure faults.

Forced regen attempts without fixing supply pressure — Shops try to burn soot before diagnosing fuel delivery.. Instead: Establish stable supply pressure first; repeated failed regens load soot and deepen derates.

Shop Notes from the Field

ProfessionalDieselRepair.com International note: SPN 3480 FMI 1 is regen fuel supply, not DEF—parts-cannon DEF pumps do nothing here; tee mechanical pressure at the HC doser supply port before ordering pumps.

Safety Warning

• HC doser fuel is diesel—keep fire extinguishers nearby during regen tests.
• Exhaust and DPF components exceed 900 °F during regen; stay clear of piping.
• Relieve fuel pressure before opening doser supply lines.

Prevention Tips

• Replace HC doser fuel filters at International PM intervals.
• Use clean ULSD in the doser supply circuit—never mix used oil or biodiesel blends above OEM limits.
• Torque doser line fittings to spec after any aftertreatment service.
• Monitor SPN 4094 soot load and perform regens before forced derate timers start.

International Field Notes for SPN 3480 FMI 1

• If hc doser fuel supply pressure 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 hc doser fuel supply pressure 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 3480 FMI 1 on A26 — many bulletin fixes address harness routing rather than sensor replacement.
• Torque hc doser fuel supply pressure 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 hc doser fuel supply pressure often clear after warm-up when moisture is the root cause.
• Compare this unit’s repair history: repeat SPN 3480 FMI 1 within 5,000 miles indicates incomplete prior repair, not a new component failure.
• If hc doser fuel supply pressure 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 hc doser fuel supply pressure 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 3480 FMI 1 on A26 — many bulletin fixes address harness routing rather than sensor replacement.
• Torque hc doser fuel supply pressure 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 hc doser fuel supply pressure often clear after warm-up when moisture is the root cause.
• Compare this unit’s repair history: repeat SPN 3480 FMI 1 within 5,000 miles indicates incomplete prior repair, not a new component failure.

Related Codes

• SPN 4094 FMI 16 — often stacks with SPN 3480 FMI 1
• SPN 3242 FMI 0 — often stacks with SPN 3480 FMI 1

FAQ

What fuel does the HC doser use?

It uses diesel from a dedicated supply circuit, separate from DEF and common rail injection.

Will SPN 3480 FMI 1 derate the truck?

Yes, if regen cannot complete and soot load rises, International calibrations progressively limit torque.

Can I regen at idle only?

Stationary regen still requires adequate HC doser supply pressure—low pressure aborts the cycle.

What does SPN 3480 FMI 1 mean on International A26?

SPN 3480 FMI 1 means hc doser fuel supply pressure - data valid but below normal operational range - moderately severe level. The ECM detected hc doser fuel supply pressure outside calibrated limits. Verify with freeze-frame data before clearing.

Can I drive with SPN 3480 FMI 1 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 3480 FMI 1?

DIY repairs start at $40–$150 for wiring or filters. Shop repairs with parts run $150 - $850. Dealer pricing runs $950+.

What is the most common cause of SPN 3480 FMI 1?

Clogged HC doser fuel filter or restricted supply line — confirm with visual inspection and live data before ordering parts.

Sources

• SAE J1939-71 — SPN 3480 parameter definition
• International OEM service information — verify by engine serial
• Mitchell1 ProDemand — 2026 labor and parts cost surveys

Related Reading

• International fault codes hub
• Diesel repair cost estimator
• HC Doser Fuel Supply Pressure diagnostic guide
• SPN 4094 FMI 16
• SPN 3242 FMI 0