SPN 3216 FMI 9
Volvo Penta
SCR/DEF System General Fault
DEF/AdBlue system fault; engine derates; warning about SCR system malfunction.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Low or contaminated DEF (AdBlue) fluid, Blocked DEF dosing injector, Failed DEF pump module, DEF quality sensor fault
How to Fix / Troubleshooting
Safety: DEF is mildly corrosive. Wear gloves and eye protection. Do not mix with fuel or oil.
- Check DEF level and age: Verify the DEF tank is adequately filled with ISO 22241-compliant fluid. Replace old DEF (over 1 year or stored hot) by draining and refilling.
- Inspect DEF lines and injector: Look for crystallized deposits around the dosing injector and lines. Carefully clean external crystals with warm water. Do not poke inside the injector nozzle.
- Run DEF system test: Using Volvo Penta diagnostics, perform a DEF pump and dosing test. Listen for pump operation and check for pressure buildup per spec.
- Check DEF quality sensor: Inspect the sensor connector on the DEF tank for corrosion or damage. Clean and reseat. If quality readings remain out of range, the sensor or pump module may need replacement.
- Clear codes and monitor: After corrective actions, clear codes and run the engine under load to confirm derate is removed.
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Repair Difficulty
Hard
4/5
Required Part
DEF Pump Module
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