This DEF metering unit flush note explains Detroit information code SPN 4335 / FMI 31 on EPA10 engines, a silent fault with no dash lamps. It signals that the Aftertreatment Control Module (ACM2) will initiate a flush of the DEF metering unit.
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 4335 / FMI 31 |
| Fault name | Silent fault (no dash lamps) – metering unit flush |
| Emissions platform | EPA10 |
| Pages | 1 |
| File size | 0.2 MB |
| Format | |
| Language | English |
| Source | TruckFaultCodes.com (© 2017); Detroit Power Service Literature |
DEF metering unit flush sections covered
The single page is informational rather than a step-by-step test, and it sets the repair order against a related code.
- Fault code header: SPN 4335, FMI 31 (silent, no dash lamps)
- Meaning: ACM2 initiates a metering unit flush procedure
- Check for SPN 3361 / FMI 7 present at the same time
- If present, repair SPN 3361 / FMI 7 first
- Reference to the SPN 3361 / FMI 7 EPA10 procedure
Applicable truck models
This note applies to Detroit DD-Series (DD13, DD15 and DD16) and Series 60 DDEC VI engines on the EPA10 aftertreatment platform served by the ACM2 control module. Related dosing procedures are published in Detroit Power Service Literature at the Detroit Diesel official website.
Who needs this DEF metering unit flush manual
A technician who sees a stored SPN 4335 / FMI 31 needs this metering unit flush note to understand it is a silent, self-initiated action and to check SPN 3361 first rather than chasing a non-existent lamp fault.
The full 1-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 4335 / FMI 31 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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