SPN 4257 FMI 4 is the Detroit diesel diagnostic trouble code for the Injector Amplifier Control Valve Cylinder 1, 2, 3 Shorted to Ground on DD Series (EPA 2007-Current) engines. This 1 page EPA10 / GHG14 PDF documents the code description, monitored parameters, dash-lamp and engine-reaction data, and the diagnostic routine drawn from Detroit Power Service Literature.
What SPN 4257 FMI 4 means
This is a fault-code description sheet for the injector amplifier control valve on cylinders 1, 2 and 3 shorted to ground, with an enabling condition of fis_nop_act greater than 1.85. It lights the MIL and CEL, applies a 25% derate, and is verified at 1400 to 1500 RPM for one minute.
Official document details
| Brand | Detroit |
|---|---|
| Model coverage | DD Series (EPA 2007-Current), also cross-referenced on Series 60 (DDEC VI, EPA 2007) |
| System / group | Diagnostic trouble codes (DTCs) |
| Fault code | SPN 4257 / FMI 4 (EPA10 / GHG14) |
| Monitored parameter | Injector amplifier control valve, cylinders 1, 2 and 3 |
| Enabling condition | fis_nop_act > 1.85 |
| Dash lamps | MIL, CEL |
| Engine reaction | 25% derate |
| Verification | Engine RPM 1400-1500 (1 minute) |
| Pages | 1 page |
| Source | Detroit Power Service Literature |
| Format | PDF, English |
Fault code description and parameters
This one-page document is a description sheet rather than a full troubleshooting tree, so it defines the monitor and its reaction.
- Monitored parameter: the injector amplifier control valve for cylinders 1, 2 and 3.
- Typical enabling condition: fis_nop_act greater than 1.85, evaluated continuously when conditions are met.
- Dash lamps and reaction: MIL and CEL with a 25% engine derate.
- Verification: run the engine at 1400 to 1500 RPM for one minute after any repair.
Cylinder 1 to 3 injector service follows the Three-Filter System procedures in Detroit Power Service Literature. Because SPN 4257 FMI 4 is a factory-defined code, following the exact injector amplifier control valve sequence and the Detroit Power Service Literature references is what keeps the repair verifiable.
Applicable trucks and engines
This procedure applies to Detroit DD Series diesel engines built to EPA 2007 and later standards, and Detroit cross-references the same code on Series 60 (DDEC VI, EPA 2007) engines. Confirm exact coverage on the Detroit Diesel official website.
Who needs this SPN 4257 FMI 4 guide
Heavy-duty technicians and workshop owners diagnosing injector amplifier control valve problems use this guide to follow the factory troubleshooting steps instead of guessing. The full PDF is available in the DiagTechPro manuals library, with a free account required to download.
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