This SPN 3609 FMI 4 document is a Detroit DD Series fault-code procedure for the DOC inlet pressure sensor circuit failed low condition on EPA10 and GHG14 engines. It captures the step-by-step resistance and continuity checks a technician performs at the Aftertreatment Control Module.
Official document details
| Brand | Detroit |
| Model coverage | Detroit DD Series (EPA 2007-Current) |
| System / group | DD Series / DTCs |
| SPN | 3609 |
| FMI | 4 |
| Condition | DOC inlet pressure sensor circuit failed low |
| Emissions level | EPA10 and GHG14 |
| Source | Detroit Power Service Literature |
| Pages | 2 |
| File size | 0.2 MB |
| Format | |
| Language | English |
SPN 3609 FMI 4 troubleshooting steps
The procedure first has you confirm whether SPN 3610/FMI 4 is also stored, which points to an open between ACM pin 117 and the diesel oxidation catalyst pressure sensor. With the ignition off you disconnect the sensor, inspect the harness for bent, spread or corroded pins, then measure resistance from sensor pin 2 to ground and to ACM pin 87 to separate a short to ground, an open wire, or a failed sensor that must be replaced.
- Fault description: DOC inlet pressure sensor circuit failed low
- Step 1 – Check for multiple codes (SPN 3610/FMI 4)
- Steps 2 to 5 – Ignition off, disconnect sensor, inspect harness pins
- Steps 6 to 7 – Resistance to ground and to ACM pin 87
- Repair or replace decision with Power Service Literature reference
Applicable truck models
This fault code applies to Detroit DD Series heavy-duty diesel engines — the DD13, DD15 and DD16 — running the EPA10 and GHG14 aftertreatment calibration with an Aftertreatment Control Module. Sensor removal references Detroit Power Service Literature, so confirm the exact wiring against the engine build on the official Detroit Diesel website.
Who needs this SPN 3609 FMI 4 manual
Diesel technicians and independent workshop owners chasing a DOC inlet pressure sensor code on a Detroit-powered truck use this procedure to avoid replacing parts unnecessarily. It suits anyone working with a diesel diagnostic tool and a digital multimeter.
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