SCR System Diagnostics

Engine-out NOx → SCR → downstream NOx, end to end

Understand SCR catalyst operation, NOx conversion, and how to isolate whether a problem is DEF delivery, dosing, temperature, NOx sensing, or the catalyst itself.

1. 1.SCR Catalyst Operation
2. 2.NOx Conversion & Ammonia Generation
3. 3.SCR Efficiency & Temperature Requirements
4. 4.DEF Dosing & Catalyst Performance
5. 5.The NOx Sensor Relationship
6. 6.Engine-Out NOx → SCR → Downstream NOx
7. 7.Isolating the Failure Layer