The Delphi Ammonia Sensor directly measures ammonia levels in the exhaust of diesel vehicles equipped with a selective catalytic reduction (SCR) aftertreatment system. The sensor output can be used to provide feedback to the SCR system helping provide optimal reduction of NOx emissions. Ammonia generally can be introduced into the exhaust flow upstream from the SCR in the form of liquid urea. The ammonia sensor detects excess ammonia in the exhaust gas allowing for more precise dosing of urea. This added precision allows for optimal SCR system efficiency and prevents the release of excess ammonia into the atmosphere.
