The DEF metering unit unclog fault sheet is the official Detroit DD Series diagnostic for the metering unit exceeding its cleaning attempts, stored under SPN 3361 FMI 8 for EPA10 calibrations. It records the monitored parameter DEF pressure, DEF air pressure, dash lamps MIL, CEL, engine reaction Derate 25%, verification by SCR Quantity Test, exactly as published by TruckFaultCodes.com (© 2017).
Official document details
| Brand | Detroit |
|---|---|
| Model coverage | Detroit DD Series diesel engines (EPA 2007-current) |
| System / Group | DD Series (EPA 2007-Current) / DTCs |
| Fault code | SPN 3361 / FMI 8 |
| Fault condition | Exhaust Fluid (DEF) Metering Unit – Exceeding Unclog Attempts |
| Monitored parameter | DEF pressure, DEF air pressure |
| Dash lamps | MIL, CEL |
| Engine reaction | Derate 25% |
| Verification | SCR Quantity Test |
| Emissions calibration | EPA10 |
| Source / Publisher | TruckFaultCodes.com |
| Year / Revision | 2017 |
| Pages | 2 |
| File size | 0.2 MB |
| Format | |
| Language | English |
Document table of contents
- Fault code identification: SPN 3361, FMI 8
- Description and monitored parameter
- Typical enabling conditions
- Troubleshooting steps
- Component inspection and repair verification
DEF metering unit unclog troubleshooting steps
The sheet has the technician compare DEF air pressure to barometric (Baro) and DEF pressure, check or replace the DEF air pressure sensor, inspect and flush the DEF nozzle and supply hose, then run the 60-second SCR air pressure test expecting a reading of 131-200 kPa (19-29 psi).
Applicable truck models
This code sheet applies to trucks powered by Detroit DD Series diesel engines built to the EPA10 emissions calibration; always match the SPN 3361 FMI 8 listing to the vehicle’s own engine family before repair. Confirm the emissions family on the vehicle emissions label, because aftertreatment and dosing hardware differs between the EPA07, EPA10 and GHG14 builds and a mismatched procedure can send you to the wrong component. For engine coverage and dealer service information, see the Detroit Diesel official website.
Who needs this DEF metering unit unclog manual
Fleet technicians and independent workshops that service Detroit DD Series engines use this DEF metering unit unclog reference to confirm the code, its enabling conditions and the correct repair before replacing parts. It is written for the mechanic making the repair decision, not the driver, and pairs with the wiring diagrams and component removal procedures Detroit publishes in Power Service Literature.
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