a method for controlling diesel engine emissions is disclosed . the diesel engine &# 39 ; s exhaust system has a diesel particulate filter and a lean no x trap . the dpf is a filter and is monitored to determine the need for regeneration . the lnt is monitored to determine the need for regeneration or desulfurization . a fuel injector is used to inject fuel upstream of the lnt under certain conditions , and a bypass may be used to bypass exhaust around the dpf to provide richer or hotter exhaust to the lnt . the sensor outputs and controls for providing the appropriate heat or fuel mix for regeneration and desulfurization may be controlled with enhancements to existing engine control circuitry .