SPN 106 FMI 3 — Air Inlet Pressure Circuit Voltage Above Normal
Air inlet pressure high-voltage codes are open-circuit diagnostics first. Air filter and duct work performed on invalid inlet pressure circuit data is the most documented misdiagnosis.
Fault Overview
SPN 106 FMI 3 indicates the air inlet pressure sensor circuit voltage is above the valid maximum — an open circuit or high-signal class fault. Open signal wire, failed sensor, unplugged connector after housing service, and harness damage are the primary causes.
Engine & Platform Coverage
Possible Causes
- 1.Open signal wire from damage near air filter housing
- 2.Failed air inlet pressure sensor with internal open element
- 3.Unplugged connector after air filter housing service
- 4.Harness damage at housing clips or adjacent brackets
- 5.Poor reference or ground at sensor connector
Wiring & Circuit Notes
Inspect the sensor connector at the air filter housing for chafe and connector lock. Confirm the connector is fully seated after any recent air filter or housing service. Verify reference and ground at the sensor connector.
DVOM Specs & Sensor Tests
Verify reference and ground at sensor connector. Check signal wire continuity from sensor to ECM. Replace sensor after circuit is proven. Evaluate filter and duct restriction only with valid inlet pressure data — restriction conclusions on invalid circuit data are unreliable.
Diagnostic Flow — FSM Sequence
AI Diesel Tech enforces this evidence-gate sequence. Each gate must pass before advancing.
4 steps locked behind Technician Mode- 1Inspect sensor connector lock — confirm fully seated after any recent housing service
- 2Verify reference and ground at sensor connector
- 3Check signal wire continuity from sensor to ECM
- 4Replace sensor after circuit is proven
- 5Evaluate filter and duct restriction only with valid inlet pressure data
Unlock the full evidence-gated diagnostic sequence, DVOM test steps, and repair procedures in Technician Mode.
Repair Steps
3 steps locked- 1Inspect sensor connector lock — confirm fully seated after any recent housing service
- 2Verify reference and ground at sensor connector
- 3Check signal wire continuity from sensor to ECM
- 4Replace sensor after circuit is proven
- 5Evaluate filter and duct restriction only with valid inlet pressure data
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.
Start Diagnosing This Fault Now
AI Diesel Tech walks you through every evidence gate in the correct order. Choose the plan that fits your shop.
Related Resources
Related Systems
Related Fault Codes
Related Sensor Locations
Common Symptoms
Related Articles
AI Diesel Tech — The Technician's Diagnostic Engine
AI Diesel Tech diagnostic logic is built by an ASE Certified Diesel Technician and engineered for professional shop use. Trusted by technicians nationwide — used in shops, fleets, and training programs.
Summary
SPN 106 FMI 3 is an open-circuit diagnosis. Circuit proof is required before any restriction or air-path conclusions.