Method and apparatus for determining a state of an exhaust gas treatment member for a motor vehicle

A method for determining a state of an exhaust gas treatment member (100) for a motor vehicle comprising: - sending of microwaves (104) in a housing (102) of the exhaust gas treatment member (100) during a period (400), in which a temperature in the housing (102) changes monotonously, and the loading state of the exhaust gas treatment member (100) within predetermined limits equal to remains, - receiving microwaves (104) in response to the transmission, - determining a waveform (303, 402) the received microwaves (104) as a function of the changing temperature, - determining the state of the exhaust gas treatment member (100) in response to the detected waveform (303, 402).