Method for detecting possible faults on a board in a system secured to said board, the system including an impedance matching circuit coupled to a contactless component (CTLR) including two output terminals (RFO1, RFO2) and two input terminals (RFI1, RFI2) connected to the impedance matching circuit and intended for delivering and receiving contactless communication signals, said detection including a first part performed by the contactless component itself and a second part comprising the execution of software implementing at least one decision tree and analysing results (I, AM, SE1, SE2) derived from the first part so as to diagnose any faults, - the first part including deliveries by the contactless component (CTLR) of test signals in the impedance matching circuit and the results including levels of physical quantities resulting from these deliveries of test signals, said levels being determined by the contactless component, - said deliveries by the contactless component (CTLR) of the test signals including deliveries in differential and/or single input/output modes, - the first part comprising: - a first delivery on the two output terminals (RFO1, RFO2) of two first test signals in phase opposition and a reception of two first corresponding signals on the two input terminals (RFI1, RFI2), and the results determined by these deliveries include the differential level of the current flowing in the impedance matching circuit as well as the differential amplitude of the two first corresponding signals received and/or a phase of one of the two first corresponding signals received, - a second delivery on a first output terminal of a second test signal and a reception on a first input terminal of a second corresponding signal, the result determined by this second delivery comprising the amplitude and/or the phase of the second corresponding signal received, - a third delivery on a second output terminal of a third test signal and a reception on a second input terminal of a third corresponding signal, the result determined by this third delivery comprising the amplitude and/or the phase of the third corresponding signal received. - the first part including deliveries by the contactless component (CTLR) of test signals in the impedance matching circuit and the results including levels of physical quantities resulting from these deliveries of test signals, said levels being determined by the contactless component, - said deliveries by the contactless component (CTLR) of the test signals including deliveries in differential and/or single input/output modes, - the first part comprising: - a first delivery on the two output terminals (RFO1, RFO2) of two first test signals in phase opposition and a reception of two first corresponding signals on the two input terminals (RFI1, RFI2), and the results determined by these deliveries include the differential level of the current flowing in the impedance matching circuit as well as the differential amplitude of the two first corresponding signals received and/or a phase of one of the two first corresponding signals received, - a second delivery on a first output terminal of a second test signal and a reception on a first input terminal of a second corresponding signal, the result determined by this second delivery comprising the amplitude and/or the phase of the second corresponding signal received, - a third delivery on a second output terminal of a third test signal and a reception on a second input terminal of a third corresponding signal, the result determined by this third delivery comprising the amplitude and/or the phase of the third corresponding signal received. - a first delivery on the two output terminals (RFO1, RFO2) of two first test signals in phase opposition and a reception of two first corresponding signals on the two input terminals (RFI1, RFI2), and the results determined by these deliveries include the differential level of the current flowing in the impedance matching circuit as well as the differential amplitude of the two first corresponding signals received and/or a phase of one of the two first corresponding signals received, - a second delivery on a first output terminal of a second test signal and a reception on a first input terminal of a second corresponding signal, the result determined by this second delivery comprising the amplitude and/or the phase of the second corresponding signal received, - a third delivery on a second output terminal of a third test signal and a reception on a second input terminal of a third corresponding signal, the result determined by this third delivery comprising the amplitude and/or the phase of the third corresponding signal received.