NOx sensor signal correction

[sheny14]

Hello ppl,

while running a NOx program at the engine test bench in a HD engine it was observed that the NOx values (ppm) before a NOx storage catalyst (NSC) was slightly less than NOx values after NSC(even after complete release of stored NOx). To find out any discrepancy relating to the sensors, measurement was done at the same location (before NSC) with two NOx sensors and observed variation in measurement values(differences ~ 5-10 ppm) at all time instances. Any suggestions on signal correction to arrive at a plausible value of stored NOx??

Thanks in advance.

Madhan