Home/Shop by Part/Fuel & Emissions/Emissions & Sensors/NOx Sensors Narrow The Number Of Models Shown By Telling Us The Year Filter Models by Year 2017 2018 2017 2016 2015 2014 2013 Choose your Western Star Model # 2017 4900EX NOx Sensors 2017 4900FA NOx Sensors 2017 4900SA NOx Sensors