SPN 107 FMI 0 — Air Filter Restriction Above Normal
Air filter restriction high is a physical inlet-path diagnosis first. Sensor replaced for a truly plugged filter, and turbo path taken for inlet restriction, are the most documented misdiagnosis patterns on this fault class.
Fault Overview
SPN 107 FMI 0 indicates the air filter or inlet restriction is above the calibrated maximum. Loaded air filter, collapsed duct, blocked precleaner, sensor bias high, snow or debris packing, and inlet path damage are the primary causes. Physical filter and duct inspection is the required first step before any sensor or powertrain conclusions.
Engine & Platform Coverage
Symptoms
- •Air filter restriction code active
- •Power loss under load with restriction code
- •Inlet restriction reading above maximum on scan tool
- •Restriction code with visible filter loading or debris
- •Derate condition triggered by inlet restriction
Possible Causes
- 1.Loaded or plugged air filter element
- 2.Collapsed intake duct reducing airflow
- 3.Blocked precleaner or air intake screen
- 4.Sensor bias high producing false restriction reading
- 5.Snow or debris packing the air intake path
- 6.Inlet path damage from impact or road debris
Diagnostic Flow — FSM Sequence
AI Diesel Tech enforces this evidence-gate sequence. Each gate must pass before advancing.
3 steps locked behind Technician Mode- 1Step 1 — Inspect and Replace Filter as Condition Requires: Physically inspect the air filter element. A loaded or plugged filter is the most common cause of restriction above normal. Replace the filter if it is loaded, damaged, or past service interval.
- 2Step 2 — Inspect Ducts and Precleaner: Inspect the intake ducts for collapse, damage, or blockage. Inspect the precleaner or air intake screen for debris, snow, or blockage. A collapsed duct or blocked precleaner can produce restriction above normal with a clean filter.
- 3Step 3 — Recheck Restriction Reading After Service: After filter replacement and duct inspection, recheck the restriction reading on the scan tool. The restriction reading should fall after a known-good filter install if the filter was the cause.
- 4Step 4 — Sensor and Circuit Proof If Restriction Remains High: If the restriction reading remains above normal with a clean filter and clear duct path, perform sensor and circuit proof. A biased restriction sensor can produce a false high reading with a clear inlet path.
Unlock the full evidence-gated diagnostic sequence, DVOM test steps, and repair procedures in Technician Mode.
Repair Steps
3 steps locked- 1Replace loaded or plugged air filter element.
- 2Repair or replace collapsed intake duct.
- 3Clean or replace blocked precleaner or air intake screen.
- 4Repair inlet path damage from impact or road debris.
- 5Replace restriction sensor after circuit proof confirms sensor bias.
Unlock full diagnostic steps, DVOM tests, and repair procedures.
Full Diagnostic Access
Verification steps, preventative measures, severity guidance, and legacy comparison are available in Technician Mode.
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Related Resources
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Summary
SPN 107 FMI 0 is a physical inlet-path fault first. Inspect and service the filter, ducts, and precleaner before any sensor or powertrain conclusions.