SPN 1636 FMI 2Turbo/AirMedium
Intake Manifold 1 Pressure — Data Erratic, Intermittent or Incorrect
Scan Tool — in guided session
DVOM Testing — in guided session
Connector Pinout — in guided session
DieselVision™ Upload photos — DieselVision™ reads diagrams, connectors, and screens with precision.
Overview
Fault Code
SPN 1636 / FMI 2
Category
Turbo/Air
Fault Type
sensor
FMI Category
data erratic
Severity
Medium
Derate Risk
No
Regen Inhibit
No
Inducement Risk
No
Component Location: MAP sensor on intake manifold — typically driver side, near front of engine.
Common Symptoms
- Intake manifold pressure reading erratic in live data
- Boost pressure monitoring unreliable
- Possible boost control fault active
- Engine may run in open-loop boost control
Root Causes
- MAP sensor intermittent failure
- MAP sensor wiring — intermittent open or short
- MAP sensor connector — loose or corroded
- Boost leak causing erratic pressure readings
- MAP sensor port plugged with oil or carbon
Full step-by-step tests, DVOM guidance, and pinout data are available inside the AI Diesel Tech diagnostic session.
AI walks you through every test — one step at a time. Plans start at $12.95/mo.
Derate Behavior
Power Derate
No
Mileage / Regen Notes
Random failure. MAP sensor port plugging increases with high idle time and poor crankcase ventilation.
System Interactions
SPN 1636 FMI 2 interacts with the following systems and may trigger cascading faults if not resolved promptly.
TSB Reference: Cummins TSB 4021756 — Intake Manifold Pressure Sensor Diagnosis
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.
OEM Notes
Cummins
X15: MAP sensor port can plug with oil mist from crankcase ventilation. Clean port during sensor replacement.
Detroit
DD15: Check EGR system for excessive soot — EGR soot can plug MAP sensor port.
PACCAR
MX-13: Inspect MAP sensor connector for moisture — common failure point in wet climates.
Related Faults in This Category
OEM System Resources
ASE Training Resources
Diagnostic Engine v7.0
Related Diagnostic Articles
Deep-dive diagnostic page: SPN 1636 FMI 2 — 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.
Get weekly diesel diagnostic tips
Real-world fault code walkthroughs, wiring tips, and shop-tested fixes — free.
No spam. Unsubscribe anytime.
Get AI-Guided Diagnosis for SPN 1636 FMI 2
The diagnostic engine walks you through every physical test — step by step, on your phone, at the truck. No guessing. No wasted parts.