This page covers the Detroit fault code SPN 5312 FMI 7, Intake Manifold Pressure Low, on DD Platform engines. It documents the monitored parameter and the six-step diagnostic flow for the intake pressure/temperature sensor.
Official document details
| Brand | Detroit |
| Model coverage | Detroit DD13, DD15 and DD16 (DD Platform) |
| System / Group | DD Series (EPA 2007-Current) / DTCs |
| Source | TruckFaultCodes.com |
| Year / Revision | 2017 (GHG14) |
| Pages | 2 |
| File size | 0.30 MB |
| Format | |
| Language | English |
SPN 5312 FMI 7 table of contents
- Fault description and 25% derate
- Air intake and Charge Air Cooler inspection
- Intake manifold vs barometric pressure
- Pressure/temperature sensor connector check
- Sensor replacement decision
The monitored parameter is Intake Manifold Pressure, enabled by intake PSI, CAC PSI and engine speed. Typical duration is 2 seconds, both MIL and CEL are on, and the engine reaction is a 25% derate.
Diagnosis begins by inspecting the entire air intake system, including the Charge Air Cooler (CAC), for leaks or restrictions. With the key on and engine off, the technician compares intake manifold pressure to barometric pressure – it should read within 0.5 psi. If not, the intake pressure/temperature sensor is replaced. Otherwise the sensor connector is inspected for bent, spread or corroded pins and repaired or the sensor replaced.
Applicable truck models
This guide applies to Detroit DD13, DD15 and DD16 engines under EPA 2007 / GHG14. Sensor removal follows the Intake Pressure/Temperature Sensor procedure in Power Service Literature. For OEM specifications and dealer support, see Detroit’s official website.
Who needs this SPN 5312 FMI 7 manual
Technicians chasing low boost, a 25% derate or an intake pressure complaint on DD Series engines use this document to confirm whether the fault is an air leak, a restriction, or the intake pressure/temperature sensor. The guide follows the factory decision-tree troubleshooting format.
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