SPN 2631 FMI 1 is the Detroit DD-Series diagnostic fault code document for the insufficient air flow event, published on TruckFaultCodes.com (copyright 2017) and archived as a 6-page PDF in the DiagTechPro library. The document is a six-page diagnostic that walks the air-management path, from the charge air cooler and wastegate to the EGR delta P sensor and the diesel particulate filter pressures.
SPN 2631 FMI 1 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) | 1 |
| Emissions calibration | All model years |
| Source | TruckFaultCodes.com (copyright 2017) |
| Pages | 6 |
| File size | 0.36 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 1)
- Insufficient air flow description
- Steps 1 to 6 – Air intake, wastegate and air supply checks
- Steps 7 to 10 – Intake manifold pressure versus barometric
- Steps 11 to 16 – EGR delta P and pipe blockage
- Steps 17 to 21 – DOC inlet and DPF outlet pressures, parked regen
The long procedure first rules out other faults, then inspects the air intake system and charge air cooler for loose clamps, leaks and restrictions, and checks the wastegate actuator and its dedicated air line. It compares intake manifold pressure with ambient barometric pressure, monitors EGR delta P voltage on pin 109, and inspects the EGR delivery, hot and crossover pipes for build-up. Final steps read Diesel Oxidation Catalyst inlet pressure on pin 87 and Diesel Particulate Filter outlet pressure on pin 72, then capture a log file during a parked regeneration before contacting the Customer Support Center.
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 1 manual
Fleet technicians chasing a low-power or restricted-airflow complaint on a Detroit DD-Series engine will use this multi-stage manual to work the whole intake and aftertreatment path in order.
The complete 6-page PDF is available in the DiagTechPro manuals library, where a free account is required to download it.
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