SPN 2631 FMI 4 is the Detroit DD-Series diagnostic fault code document for the intake manifold pressure sensor circuit failed low event, published on TruckFaultCodes.com (copyright 2017) and archived as a 2-page PDF in the DiagTechPro library. The document covers a failed-low circuit on the intake manifold pressure/temperature sensor, testing the harness wiring and resistance to ground back to the Motor Control Module (MCM).
SPN 2631 FMI 4 document details
| Brand | Detroit |
| Model coverage | Detroit DD-Series (DD13, DD15 and DD16), EPA 2007 and later |
| System / group | DD Series (EPA 2007-Current) / DTCs |
| Fault code (SPN) | 2631 |
| Failure mode (FMI) | 4 |
| Emissions calibration | All model years |
| Source | TruckFaultCodes.com (copyright 2017) |
| Pages | 2 |
| File size | 0.22 MB |
| Format | |
| Language | English |
The page records the official identifiers so a technician can confirm the exact code and calibration against the diesel diagnostic tool before starting any repair.
Document table of contents
- Fault code identification (SPN 2631 / FMI 4)
- Circuit failed low description
- Steps 1 to 2 – Harness connector inspection
- Steps 3 to 4 – Voltage measurement (pins 1 and 4)
- Steps 5 to 7 – MCM disconnect and resistance check
- Intake pressure/temperature sensor removal reference
After disconnecting the intake manifold pressure/temperature sensor and inspecting the harness for bent, spread or corroded pins, the technician turns the ignition on and measures the voltage between pins 1 and 4 against a 5.25-volt threshold. The later steps turn the ignition off, disconnect the MCM 120-pin connector and measure resistance between pin 1 of the sensor harness and engine ground against a 3-ohm limit. The outcome either repairs the wire to pin 87 of the MCM connector or replaces the sensor using the referenced removal procedure.
Applicable truck models
This document applies to Detroit DD-Series diesel engines in the EPA 2007-and-later range, typically the DD13, DD15 and DD16 as covered by the All model years calibration shown on the file. Confirm the engine calibration and connector layout for your chassis on the official Detroit engine site before ordering parts.
Who needs this SPN 2631 FMI 4 manual
Workshop technicians facing a low intake-pressure reading on a Detroit DD-Series engine will use this page to isolate a shorted wire from a genuinely faulty sensor.
The complete 2-page PDF is available in the DiagTechPro manuals library, where a free account is required to download it.
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