Using a Stand-alone NOx meter to diagnose Diesel SCR Systems. Due to outlet NOx sensors having 100% crosstalk to Ammonia, the outlet NOx sensor may or may not be accurate when the system malfunctions. Without knowing true NOx out the tailpipe, you can't accurately diagnose the system. The sensor in a NOx bench doesn't have crosstalk to Ammonia, so you can use it to work on SCR Systems.
