SPN 1172 FMI 2 is the Detroit DD Series fault-code troubleshooting sheet that documents a coolant temperature and compressor inlet temperature plausibility error on the Motor Control Module engine platform. This 1-page reference reproduces the fault-code identification and the factory decision tree so a technician can diagnose the concern before replacing parts.
Official document details
| Brand | Detroit |
|---|---|
| Model coverage | Detroit DD Series (EPA 2007-Current) |
| System / Group | DD Series (EPA 2007-Current) / DTCs |
| Fault code | FMI 2 under SPN 1172 (ALL YEARS) |
| Source | Detroit fault-code literature via TruckFaultCodes.com, © 2017 |
| Pages | 1 |
| Format | |
| Language | English |
SPN 1172 FMI 2 fault description
This single-page sheet addresses an implausible comparison between coolant temperature and turbocharger compressor inlet temperature. The technician disconnects the turbocharger compressor inlet temperature sensor and inspects its connector for bent, damaged or corroded pins. If damaged pins are found, they are repaired as necessary; if the connector is sound, the turbocharger compressor inlet temperature sensor is replaced, following the sensor removal procedure in the service literature. The sheet keeps the diagnosis short because the plausibility check points almost entirely at the inlet temperature sensor circuit.
The SPN 1172 FMI 2 sheet identifies the following likely causes and check points:
- Bent, damaged or corroded pins at the sensor connector
- Faulty turbocharger compressor inlet temperature sensor
Document table of contents
- Fault code identification
- Turbocharger compressor inlet temperature sensor inspection
- Sensor connector repair or replacement
Applicable truck models
This troubleshooting sheet applies to Detroit DD Series engines built from EPA 2007 to current that use the Motor Control Module (MCM) and Common Powertrain Controller architecture. Confirm the engine’s emissions family and calibration against the manufacturer’s official documentation at the Detroit engine website before repairs.
Who needs this 1172 FMI 2 manual
Heavy-duty diesel technicians, fleet shops and mobile mechanics who retrieve this code on a Detroit DD engine need this manual to follow the factory decision tree instead of guessing. It is written for anyone using DDDL or an equivalent diesel diagnostic tool who wants the exact test values before condemning a component.
The full 1-page PDF of this procedure is available in the DiagTechPro manuals library; a free account is required to download.
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