SPN 3361 FMI 11 — DEF dosing unit — root cause unknown
What it means: DEF dosing unit — root cause unknown.
How serious / can you keep driving: Serious. Power derate likely — plan to stop soon.
Check first: Pressure log the DEF supply
Don't risk it — look up listed providers near you and give them this SPN/FMI when you call.
Listed providers nearest Louisville, KY
Closest first. Tell them SPN 3361 FMI 11 and what the truck is doing. RoadService.app lists these providers and does not employ them or carry out the repair.
- 0.0 mi away — based in Louisville, KY · (502) 773-1159
- 0.0 mi away — based in Louisville, KY · (502) 447-1234
- 0.0 mi away — based in Louisville, KY · (502) 648-6725
Applies to: Sae
What SPN 3361 FMI 11 means
DEF dosing unit — root cause unknown.
How serious is it?
Serious. Power derate likely — plan to stop soon.
Most likely causes
- Intermittent dosing fault
- Pump/valve
- Line pressure swing
First moves (roadside)
- Pressure log the DEF supply
- Check dosing valve electrical
FAQ
DEF dosing unit — root cause unknown.
Serious — Power derate likely — plan to stop soon.
The most common cause is: Intermittent dosing fault. Other possibilities include Pump/valve; Line pressure swing.
Power derate likely — plan to stop soon. When in doubt, get a qualified mobile diesel tech on the truck before continuing.
Related codes
Codes that commonly appear alongside SPN 3361 FMI 11, or share the same subsystem.
- DEF Dosing Unit — Not Responding Properly (SPN 3361 FMI 7)
- DEF dosing valve solenoid — open circuit (SPN 3361 FMI 5)
- DEF dosing valve solenoid — short to ground (SPN 3361 FMI 6)
- DEF dosing unit — condition exists (SPN 3361 FMI 31)
- SCR Operator Inducement — Severe Derate Active (SPN 5246 FMI 0)
- Aftertreatment 1 Diesel Particulate Filter Differential Pressure - Data Valid But Above Normal Operating Range, Most Severe Level (DPF severely restricted / plugged) (SPN 3251 FMI 0)
- Aftertreatment 1 Diesel Exhaust Fluid Quality - Data Valid But Below Normal Operating Range, Most Severe Level (DEF quality/concentration incorrect) (SPN 4364 FMI 1)
- DPF Differential Pressure — Data Erratic (SPN 3251 FMI 2)
Same symptom: DEF / SCR fault
Other codes in the DEF and SCR chain — the ones that end in an inducement countdown.
- Reductant System Performance Bank 1 (P204F) · Aftertreatment & Emissions
- Reductant Quality Deviation (P20EA) · Aftertreatment & Emissions
- DEF tank level low (SPN 1761 FMI 18) · Aftertreatment & Emissions
- DEF tank temp sensor — voltage high (SPN 3031 FMI 3) · Aftertreatment & Emissions
- Upstream NOx sensor — internal failure reported (SPN 3216 FMI 12) · Aftertreatment & Emissions
- SCR inlet NOx sensor — erratic (SPN 3216 FMI 2) · Aftertreatment & Emissions
Find a mechanic or related guides
General diagnostic guidance for heavy-duty diesel engines (Cummins, Detroit, PACCAR, Volvo, Mack). Not a substitute for a scan-tool diagnosis on your specific truck.