Isb scr conversion efficiency nightmare

[dslmchnc]

(10-12-2018 )Rawze Wrote:  NOx sensors, as they get some age on them, tend to read incorrectly, never throwing a fault.

Could also be bad DEF fluid or clogged DEF nozzle?.

Def has been sampled and tested with our refractometer. Def dosing injector has been flow tested and cleaned. The inlet nox is consistently reading higher than the outlet during the scr performance test. Should I suspect the inlet nox sensor? We replaced the outlet when the scr was cleaned.
Thanks