This HC doser fuel supply sheet documents Detroit SPN 3480 FMI 1, an abnormal supply pressure that carries a 10 percent derate. It runs from a related-code check through leak inspection to a measured priming-port test. Follow the numbered steps.
Official document details
| Brand | Detroit |
|---|---|
| Model coverage | DD Series (EPA 2007-Current); also filed under Series 60 (DDEC VI – EPA 2007) |
| System / Group | DTCs — Hydrocarbon (HC) Doser Fuel Supply Pressure Abnormal |
| Fault code | SPN 3480 / FMI 1 |
| Source | www.TruckFaultCodes.com (© 2017) |
| Pages | 4 |
| File size | 0.3 MB |
| Format | |
| Language | English |
HC doser fuel supply diagnostic guide
After safing the vehicle, the technician confirms SPN 3480 FMI 14 is not present, inspects the doser block for leaks and runs a purge routine of up to three attempts. With the cutoff at 100 percent, compensation pressure is compared against the charted Gen 1 and Gen 2 windows to decide between a low-pressure fuel test, a new sensor and a new metering unit. Tool J-48876 then checks the priming port at 70 to 90 psi at idle and 100 to 140 psi at 1800 rpm before a parked regeneration verifies the repair.
Document table of contents
- Fault code identification: SPN 3480, FMI 1
- Description, monitored parameter and 10 percent derate
- Related-code check and leak inspection
- Live pressure monitoring and priming-port test
- Parked regeneration and verification
Applicable truck models
This procedure applies to Detroit DD Series engines built for EPA 2007 and later, covering all model years (EPA07, EPA10 and GHG14) as printed on the document cover, and the identical SPN/FMI sheet is also filed under Detroit Series 60 (DDEC VI, EPA 2007). Confirm the emissions platform on your truck and cross-check the connector and pin numbers against the official Detroit engine support site before making any repair.
Who needs this HC doser fuel supply manual
A diesel technician on any Detroit DD model year with an abnormal supply pressure complaint uses this sheet to combine leak checks, live pressure readings and a priming-port test before committing to a repair.
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