SPN 3609 FMI 2 is the Detroit DD Series diagnostic trouble code for a DPF inlet pressure sensor plausibility error. This manual page documents the official Detroit troubleshooting sequence, including exhaust and Aftertreatment Device inspection and the diesel diagnostic tool voltage service routine monitoring the DPF inlet pressure signal (P_DPF_IN), so a technician can locate the fault accurately. It is written for workshops running the Detroit Diesel Diagnostic Link.
Official document details
| Brand | Detroit |
|---|---|
| Model coverage | DD Series (EPA 2007-Current) and Series 60 (DDEC VI – EPA 2007) |
| System / Group | DTCs / diagnostic trouble codes |
| Emission platform | EPA07 |
| Pages | 3 |
| File size | 0.3 MB |
| Format | |
| Language | English |
What the SPN 3609 FMI 2 manual covers
The procedure in this manual walks through the following checks:
- Fault description for the inlet pressure sensor circuit
- Exhaust and Aftertreatment Device (ATD) leak inspection
- Connecting the diesel diagnostic tool and the voltage service routine
- Monitoring the DPF inlet pressure signal (P_DPF_IN)
- ATD 10-pin, VIH 31-pin and MCM 120-pin harness checks
- Connector corrosion, bent and spread-pin inspection
Applicable Detroit truck models
The procedure applies to Detroit DD Series engines on the EPA 2007-Current platform and to Series 60 engines with DDEC VI, as listed in the source document. Diagnosis covers the DPF inlet pressure hose, the ATD 10-pin connector, the Vehicle Interface Harness 31-pin connector and the MCM 120-pin connector, all referenced in Detroit Power Service Literature. For engine data and bulletins, consult the official Detroit Diesel support site.
Who needs this SPN 3609 FMI 2 guide
Diesel technicians and aftertreatment specialists on a Detroit DD Series engine need this 3609 FMI 2 manual to separate a genuine inlet pressure sensor fault from a harness or connector problem before any part is replaced, using the recorded voltages as evidence.
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