SPN 4374 FMI 3 is the Detroit Diesel diagnostic trouble code set when the DEF pump speed signal reads above its measurement range on DD Series (EPA 2007-current) engines. This 2-page troubleshooting sheet lists the fault definition, the relevant monitor or note data, and a numbered diagnostic routine that ends in the correct wiring or component repair. It is drawn from TruckFaultCodes.com (© 2017) and applies to the GHG14 emissions calibration.
Official document details
| Brand | Detroit Diesel |
|---|---|
| Model coverage | DD Series engines (EPA 2007-current) |
| System / group | DTCs — DEF pump speed circuit |
| Suspect parameter (SPN) | SPN 4374 |
| Failure mode (FMI) | DEF pump speed signal above range |
| Emissions calibration | GHG14 |
| Verification | SCR ADS self-check |
| Source / copyright | TruckFaultCodes.com, © 2017 |
| Pages | 2 |
| File size | 0.2 MB |
| Format / language | PDF / English |
SPN 4374 FMI 3 table of contents
The technician confirms no other codes are present, then inspects the DEF pump harness and connector for damage or corroded pins. A Selective Catalytic Reduction Airless Dosing System (SCR ADS) self-check is run to see whether DEF pump speed and DEF pressure values return to normal range. A failed test points to replacing the DEF pump; if the self-check still fails afterward, a test ACM2.1 is installed and, as a last step, Detroit Customer Support is contacted at 800-445-1980.
- Fault code header and log-file note
- DEF pump four-pin connector pin-out
- Troubleshooting steps 1 to 8
- SCR ADS self-check verification
- DEF pump and ACM2.1 replacement, support contact
Applicable truck models
This sheet is part of the DD Series diagnostic trouble code library and addresses the DEF pump speed feedback circuit. The SPN 4374 FMI 3 procedure applies to Detroit DD Series (EPA 2007-current) engines running the GHG14 calibration, and the same code index is cross-referenced under the Detroit Series 60 (DDEC VI, EPA 2007) fault-code set. For engine identification and warranty details, see the Detroit Diesel official site.
Who needs this 4374 FMI 3 manual
It helps technicians decide, from a single self-check, whether an above-range DEF pump speed signal is a pump, wiring or controller problem on Detroit DD Series trucks. Clear pass and fail criteria keep parts from being replaced on guesswork.
The full 2-page PDF is available in the DiagTechPro manuals library; a free account is required to download.
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