International · HC Doser Fuel Supply PressureHigh

International SPN 3480 FMI 1: HC Doser Fuel Supply Pressure Low

SPN 3480 FMI 1 (FMI 1) — HC Doser Fuel Supply Pressure - Data Valid But Below Normal Operational Range - Moderately Severe Level

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Quick Answer

SPN 3480 FMI 1 means HC doser fuel supply pressure is below normal during regen. Verify pump voltage, filter restriction, and mechanical pressure before replacing the doser supply module.

Overview: International SPN 3480 FMI 1

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.

Repair Snapshot

Time

2 - 5 Hours

Difficulty

Advanced

Parts Cost

$150 - $850

Dealer Labor

$950+

Tools Required

  • ServiceMaxx
  • Noregon JPRO
  • Fuel Pressure Gauge
  • Line Wrench Set

What SPN 3480 FMI 1 Means

SPN 3480 FMI 1 on International A26 and N13 engines means HC doser fuel supply pressure is valid but below the moderately severe threshold. The seven-point doser cannot atomize fuel for DPF regen, so regen requests fail, soot load climbs, and the truck faces active torque derates or a forced shutdown to protect the aftertreatment system.

Symptoms Drivers Notice

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

Most Likely Root Causes

Clogged HC doser fuel filter or restricted supply line

Common

Low flow at the doser pump drops supply pressure below the moderately severe threshold during regen.

Weak HC doser supply pump

Common

Worn pump internals cannot maintain 400+ kPa when the doser valve opens during active regen.

Air ingestion at doser fuel line fittings

Occasional

Loose banjo bolts or cracked hoses introduce air that collapses pressure spikes the ECM monitors.

Common Misdiagnoses (Don't Waste Parts)

Replacing the DEF pump or SCR injector

Why it happens: Technicians assume all aftertreatment fluids share one pump.

Do this 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

Why it happens: Shops try to burn soot before diagnosing fuel delivery.

Do this instead: Establish stable supply pressure first; repeated failed regens load soot and deepen derates.

Master Tech Commentary

Mechanic's Notes

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.

Step-by-Step Diagnostic Procedure

  1. Step 1: Connect ServiceMaxx or Noregon JPRO and read SPN 3480 live pressure during a commanded regen attempt.
  2. Step 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.
  3. Step 3: Inspect the doser fuel filter and replace if differential pressure exceeds 15 psi; prime until ServiceMaxx shows stable supply above 400 kPa.
  4. Step 4: Check for leaking doser fuel lines at the metering pump and one-way check valve—air ingestion drops pressure below FMI 1 limits.
  5. Step 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.

Professional service / OEM-level scan tools are recommended before clearing this fault for good.

Live Data & Freeze-Frame Tips

During a commanded regen in ServiceMaxx, log SPN 3480 pressure alongside doser valve command. Pressure should climb above 400 kPa within 10 seconds of valve opening. Flat readings indicate pump or filter problems, not doser nozzle clogging alone.

Safety Warnings

  • 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.

When to Limp In vs Tow

Tow if soot load exceeds 100%, repeated regen aborts trigger severe derate, or the engine protects to idle-only due to aftertreatment strategy.

Prevention Tips for Fleets & Owner-Operators

  • 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.

Related Fault Codes

SPN 4094 FMI 16 — DPF Soot Load

High DPF soot load follows failed regens caused by low HC doser supply pressure.

SPN 3242 FMI 0

High DPF intake temperature may appear when regen attempts run incomplete.

Frequently Asked Questions

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.

Where is the doser fuel filter?

Typically on the frame rail near the doser supply pump—consult the A26/N13 service diagram for exact location.

How is this different from SPN 94?

SPN 94 monitors engine fuel delivery pressure; SPN 3480 is specific to the aftertreatment HC doser supply circuit.

Typical repair cost?

Filter and line repairs run $200-$500; supply pump replacement can reach $800-$1,200 with labor.

More International codes on this system

All International fault codes

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