[amidgeha]

nox Exceedence - Root Cause Unknown

The selective catalytic reduction system reduces oxides of nitrogen (NOx) emissions by injecting a metered amount of diesel exhaust fluid or reductant

Cause:
Exhaust Leaks
Fuel contamination
Faulty Diesel Particulate Filter (DPF)
Faulty NOx Sensor
Diesel Exhaust Fluid
Faulty Selective Catalyst Reduction (SCR) Catalyst

Symptoms:
Check engine light