DIAGNOSTIC DEVICE FOR EXHAUST GAS AFTERTREATMENT DEVICE, DIAGNOSTIC METHOD FOR EXHAUST GAS AFTERTREATMENT DEVICE, AND DIAGNOSTIC PROGRAM FOR EXHAUST GAS AFTERTREATMENT DEVICE

A diagnostic device for an exhaust gas aftertreatment device includes a temperature detection device that detects a filter inlet-side temperature and a filter outlet-side temperature, a differential pressure detection device that detects a differential pressure between a filter inlet-side pressure and a filter outlet-side pressure, an intake air pressure detection device that detects an intake air pressure of an engine, and a controller that determines a malfunction in an exhaust gas aftertreatment device based on values detected by the temperature detection device, the differential pressure detection device, and the intake air pressure detection device.