AdBlue Crystallisation may arise from multiple operating, fluid, sampling or analytical causes. The pattern, rate of change and correlated evidence determine the most credible explanation.
Start with the observation
Confirm sample identity, method, units, service interval and historical baseline. A single abnormal parameter rarely confirms root cause, and a plausible explanation should predict other evidence that can be checked.
Differential diagnosis
| Possible cause | Supporting indicators | Confirming tests | Immediate response | Long-term corrective action |
|---|---|---|---|---|
| Evaporation | White deposits | adblue urea concentration | Use compatible handling practices | Correct the confirmed source rather than the isolated number |
| Temperature cycling | SCR warnings | adblue refractive index | Check concentration and contamination | Establish a follow-up sampling point and timing |
| Dosing leakage | Blocked injector | elemental analysis icp oes | Use compatible handling practices | Document maintenance so the post-action trend can be evaluated |
| Incorrect concentration | White deposits | adblue urea concentration | Check concentration and contamination | Correct the confirmed source rather than the isolated number |
Confirming and supporting evidence
Supporting indicators
- White deposits
- SCR warnings
- Blocked injector
Immediate and corrective actions
| Stage | Objective | Action |
|---|---|---|
| 1 · Verify | Confirm the observation is comparable | Check asset, compartment, sample point, units, method, interval, top-up and maintenance history. |
| 2 · Protect | Control immediate equipment or safety risk | Use compatible handling practices; Check concentration and contamination |
| 3 · Diagnose | Find the source using independent evidence | Use adblue urea concentration, adblue refractive index, elemental analysis icp oes and relevant inspection evidence. |
| 4 · Correct and confirm | Remove the cause and prove effectiveness | Correct the confirmed source rather than the isolated number; Establish a follow-up sampling point and timing; Document maintenance so the post-action trend can be evaluated |
- 01Use compatible handling practices
- 02Check concentration and contamination
- 03Correct the confirmed source rather than the isolated number
- 04Establish a follow-up sampling point and timing
- 05Document maintenance so the post-action trend can be evaluated
False positives and context checks
- Non-representative sample
- Changed method or laboratory
- Recent top-up or overhaul
- Container or sampling-tool contamination
References and method context
References identify authoritative source families; they do not reproduce protected procedures or acceptance tables. Verify the current official edition before procedural or conformity use.