DEF Injector Nozzle Crystallization Detected

What this code means

The DEF injector nozzle has crystallized DEF deposits reducing spray quality and dosing accuracy.

Symptoms

• Check Engine Light
• White crystalline deposits visible near exhaust
• DEF dosing less effective
• SCR efficiency declining
• Increased NOx emissions
• Exhaust backpressure rising

Common causes

• Normal DEF crystallization over time
• Exhaust temperature too low during dosing
• DEF concentration incorrect
• Injector nozzle partially blocked
• Dosing occurring during low exhaust flow

Diagnostic steps

1. Inspect DEF injector nozzle for crystallization
2. Check exhaust temperature at injector location
3. Test DEF quality with refractometer
4. Monitor dosing quantity vs commanded
5. Inspect decomposition tube condition

Repair notes

Remove and clean DEF injector nozzle. Replace decomposition tube if deposits are severe. Address low exhaust temperature cause.

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