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Fault Code Reference

SPN 102 FMI 18Turbo / BoostHighInducement Risk

Intake Manifold Pressure Too Low

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Overview

Fault Code

SPN 102 / FMI 18

Category

Turbo / Boost

Severity

High

Derate Risk

Yes

Regen Inhibit

No

Inducement Risk

Yes — SCR inducement possible

Component Location: Intake manifold pressure sensor on intake manifold top or side (ISX15 — passenger side near front); intake air cooler outlet (DD15)

Common Symptoms

  • Low boost pressure under load, significant power loss especially on hills or when pulling, black smoke during acceleration, turbo not spooling properly or slow to spool, engine struggles to maintain speed, audible air leak or hissing sound from engine compartment, poor throttle response, increased exhaust temperatures, possible turbo surge or flutter noise

Root Causes

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Derate Behavior

Power Derate

Yes

SCR Inducement Risk

If left unresolved, this fault may trigger SCR inducement — a progressive derate enforced by the ECM to ensure emissions compliance.

Mileage / Regen Notes

This fault typically does NOT directly inhibit active regeneration. However, low boost pressure affects exhaust temperature management — the ECM may struggle to reach or maintain target regen temperatures, causing regen attempts to time out or abort. If the condition is severe, the ECM may delay regen initiation until boost performance improves. Additionally, if soot loading increases due to poor combustion from low boost, the DPF may reach critical levels faster, potentially forcing a parked regen or service regen requirement. Monitor soot load percentage closely while diagnosing.

System Interactions

SPN 102 FMI 18 interacts with the following systems and may trigger cascading faults if not resolved promptly.

TSB Reference: No confirmed universal TSBs — verify in OEM service portal for specific engine application. Common service bulletins exist for: Cummins ISX charge air cooler end tank failures, Detroit DD13/DD15 turbo actuator calibration and boot failures, Paccar MX VGT actuator updates. Always check for applicable campaign or extended coverage on turbocharger and CAC components.

Common Diagnostic Mistakes

Replacing the sensor without verifying wiring continuity and supply voltage first.

Clearing codes without identifying and resolving the root cause — the fault will return.

Ignoring related active faults — cascading faults often share a root cause.

Skipping the connector inspection — corrosion and damaged pins are a leading cause of sensor faults.

Condemning the ECM before exhausting all wiring and component tests.

Deep-dive diagnostic page: SPN 102 FMI 18 — Full FSM Sequence & Repair Steps — includes wiring notes, sensor specs, and gated repair procedures.

Authority References

Diagnostic procedures on this page are informed by OEM service literature and industry standards.

Cummins QuickServe OnlineOfficial Cummins service manuals, fault code lookup, and TSB database.Detroit Diesel DiagnoCentralDetroit Diesel diagnostic procedures, DDDL documentation, and service literature.PACCAR MX Engine ServicePACCAR MX-11 and MX-13 engine service documentation and DAVIE diagnostic guides.Volvo/Mack Tech ToolVolvo and Mack engine fault code reference and PTT/Tech Tool diagnostic procedures.ASE — Diesel Truck Technician CertificationNational Institute for Automotive Service Excellence — T2 Diesel Engines certification standards.EPA Aftertreatment & Emissions GuidelinesU.S. EPA heavy-duty diesel aftertreatment compliance, DPF/SCR regulations, and NOx standards.

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