DEF Dosing Valve Circuit Open (J1939)
What does VOLVO-MACK-SPN3361-FMI5 mean?
The VOLVO-MACK-SPN3361-FMI5 (Volvo/Mack D/MP Series) diesel fault code means: DEF Dosing Valve Circuit Open (J1939). This is a serious severity code.
Common Symptoms
- Check Engine Light illuminated
- Possible engine derate
- Warning message on driver display
- System-specific warning lamp (DPF/DEF/coolant/etc.)
Probable Causes (Ranked by Likelihood)
- DEF doser open-circuit or harness damage Very Likely
- DEF doser solenoid failed internally Likely
- Connector corrosion at doser Possible
- ACM output driver fault Less Likely
Step-by-Step Diagnostic Procedure
Connect Volvo PTT or Mack Guided Diagnostics and verify DEF doser open-circuit fault.
Measure doser solenoid resistance (spec per service manual).
Inspect connector and pin integrity at the doser.
If solenoid and wiring test good, suspect ACM driver; further testing required.
Run DEF dosing test after repair.
Frequently Asked Questions
What does Volvo/Mack code SPN3361-FMI5 mean?
Volvo/Mack code SPN3361-FMI5 (DEF Dosing Valve Circuit Open (J1939)) is a serious-severity diagnostic trouble code set on D11/MP7, D13/MP8, and D16/MP10 diesel engines in Volvo VNL/VNR and Mack Anthem/Pinnacle/Granite/Titan trucks. It indicates a fault in the DEF doser system and should be read with Volvo Premium Tech Tool (PTT) or Mack Guided Diagnostics.
Can I drive a Volvo or Mack truck with code SPN3361-FMI5?
Short distances may be acceptable to reach a repair facility, but the fault will escalate to derate (typically 55 mph then 5 mph on aftertreatment faults). Do not defer diagnosis beyond a shift.
How much does it cost to fix Volvo/Mack code SPN3361-FMI5?
Typical repair falls in the range $400-$2,500. Sensor/wiring repairs are at the low end; EGR cooler, NOx sensor set, DEF pump, injector, or head work runs at the high end. Volvo PTT or Mack Guided Diagnostics is normally required for calibration and parameter programming.