This Detroit DEF pump pressure document covers fault code SPN 4334 / FMI 7 on EPA10 engines, a low-pressure condition that drives a 25% derate. The five-page procedure checks fluid quality, gauges the air feed, and tests the pump and switching valve.
Official document details
| Brand | Detroit |
| Model coverage | Detroit DD-Series (DD13, DD15, DD16) and Series 60 (DDEC VI) |
| System / Group | DD Series (EPA 2007-Current) / DTCs |
| Fault code | SPN 4334 / FMI 7 |
| Fault name | DEF pressure low |
| Emissions platform | EPA10 |
| Pages | 5 |
| File size | 0.3 MB |
| Format | |
| Language | English |
| Source | TruckFaultCodes.com (© 2017); Detroit Power Service Literature |
Detroit DEF pump pressure sections covered
The routine starts at DEF fluid quality and the air supply, then isolates the pump, its switching valve and the suction line.
- Check DEF fluid for contamination and other SCR faults
- Confirm vehicle air pressure reaches 689 kPa (100 psi)
- Gauge the pump air feed at 517 to 586 kPa (75 to 85 psi)
- Compare DEF pressure to barometric (Baro) and DEF air pressure
- Test the tank return for the pneumatic switching valve
- Test the pump to 496 kPa (72 psi) and inspect the suction line
Applicable truck models
These steps cover Detroit DD-Series (DD13, DD15 and DD16) and Series 60 DDEC VI engines on the EPA10 platform with the ACM2 aftertreatment control module. Pump and switching-valve removal chapters are in Detroit Power Service Literature at the Detroit Diesel official website.
Who needs this Detroit DEF pump pressure manual
This DEF pump pressure manual is for the technician resolving SPN 4334 / FMI 7, where contaminated fluid, an air leak or a failed pump each demand a different repair on this five-page path.
The full 5-page PDF is available in the DiagTechPro manuals library; a free account is required to download. For workshop reference, Detroit documents the matching component removal and installation steps for SPN 4334 / FMI 7 in Power Service Literature, and technicians should keep the wiring pin numbers shown in this sheet on hand while testing on the bench.
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