The DEF metering unit restriction fault sheet is the official Detroit DD Series diagnostic for a metering unit that cannot clear an internal blockage, stored under SPN 3361 FMI 7 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 7 |
| Fault condition | Diesel Exhaust Fluid (DEF) Metering Unit – Unable to Clear Restriction |
| 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 | 5 |
| File size | 0.4 MB |
| Format | |
| Language | English |
Document table of contents
- Fault code identification: SPN 3361, FMI 7
- Description and monitored parameter
- Typical enabling conditions
- Troubleshooting steps
- Component inspection and repair verification
DEF metering unit restriction troubleshooting steps
The sheet has the technician compare DEF air pressure to barometric pressure, inspect and flush the compressed-air supply screen, nozzle supply hose and metering-unit air channel with warm water using DEF test kit W060589001900, and remove the diffuser heater to dissolve DEF crystals before re-testing.
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 7 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 restriction manual
Fleet technicians and independent workshops that service Detroit DD Series engines use this DEF metering unit restriction 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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