SPN 655 FMI 7 is the Detroit diagnostic trouble code for Injector Cylinder #5 Needle Control Valve Sticks Open on DD Series (EPA 2007-current) engines. This 8-page PDF, published by TruckFaultCodes.com (© 2017), reproduces the official Detroit fault-code sheet — the description table plus the full sixteen-step troubleshooting routine. It is a diagnostic reference for shop use, not a substitute for Detroit Power Service Literature.
Official document details
| Brand | Detroit |
| Model coverage | DD Series (EPA 2007-current); also Series 60 (DDEC VI) |
| System / group | DTCs — fuel injection |
| Fault SPN | 655 |
| Fault FMI | 7 |
| Emissions | GHG14 |
| Source | TruckFaultCodes.com fault-code sheet (© 2017) |
| Dash lamps | MIL, CEL |
| Engine reaction | Derate 25% |
| Pages | 8 |
| File size | 0.6 MB |
| Format | |
| Language | English |
Document table of contents
- Fault code header and monitored parameter
- Enabling conditions, dash lamps and engine reaction
- Troubleshooting Steps 1 through 16
- Rear fuel injector harness 14-pin resistance charts
- Rocker cover and injector harness removal references
- MCM 120-pin connector inspection
- Test MCM installation and 30-minute road test
Applicable truck models
The routine applies to Detroit DD Series engines — the DD13, DD15 and DD16 family — built on the EPA 2007-current platform, and the sheet cross-references Series 60 (DDEC VI) applications. It covers the GHG14 emissions calibration named in the file. Verify the engine serial number and emissions family against build records before servicing; model and rating data are published by Detroit on its official engine site.
SPN 655 FMI 7 troubleshooting steps
This procedure runs sixteen ordered steps. It starts by checking for companion codes SPN 168 or 723 and warming the engine above 71°C (160°F). The technician disconnects the rear fuel injector harness 14-pin connector, inspects the pins for water or oil intrusion, and measures the needle control valve resistance with a diesel diagnostic tool. Out-of-range readings lead to the rocker cover and a direct injector-side check; in-range readings move on to the MCM 120-pin connector inspection and a test MCM (extension harness J-49120) before a 30-minute road test.
Who needs this SPN 655 FMI 7 manual
Independent diesel technicians, fleet service teams and Detroit DD Series owners use this sheet to confirm a needle control valve fault before condemning an injector or the MCM. Following the documented resistance checks avoids replacing good parts and supports a warranty claim to the Detroit Customer Support Center.
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