Method for detecting an identifier (Id) for starting a motor vehicle, said motor vehicle comprising a first antenna and said identifier (Id) comprising a second antenna, according to which said method comprises: - transmitting, by means of said first antenna, a first Bluetooth Low EnergyTM signal toward said identifier (Id) at a nominal power; - measuring the power (P1') of said corresponding signal (Sg1') received by the second antenna of said identifier (Id); - the identifier (Id) comparing said measured power (P1') with a threshold power (Ps), said threshold power (Ps) corresponding to a threshold distance (ds) from said first antenna which is smaller than the radius of a circle inscribed in the passenger compartment of the motor vehicle, said circle being centred on said first antenna; - said first antenna receiving, via the Bluetooth Low EnergyTM communication protocol, the result of the comparison between the powers P1' and Ps; - enabling the starting of the motor vehicle if the measured power (P1') is greater than or equal to said threshold power (Ps); the method further comprising: - positioning said identifier (Id) at a reference position (Por) of the motor vehicle; - said first antenna being placed at a predefined distance from the reference position (Por); - adjusting the communication channel between the first antenna and the second antenna of said identifier (Id) with the first antenna on the first use of said identifier (Id) with the motor vehicle and/or on request, the adjustment comprising: ∘ transmitting, by means of the first antenna, a first calibration signal (Sgc) at the nominal power toward the second antenna; ∘ measuring the power (P2') of said corresponding reception signal (Sgr) received by said second antenna, and sending said measured power (P2') toward said first antenna; ∘ comparing said measured power (P2') with a theoretical power (Pt) corresponding to said predefined distance, using a regression curve (Cn) of power as a function of distance; ∘ determining whether there is an offset (Off) between said measured power (P2') and said theoretical power (Pt); ∘ if there is an offset (Off), modifying the nominal power of the first transmitted Bluetooth Low EnergyTM signal (Sgl) as a function of said offset (Off), or modifying the threshold power (Ps) as a function of said offset (Off). - transmitting, by means of said first antenna, a first Bluetooth Low EnergyTM signal toward said identifier (Id) at a nominal power; - measuring the power (P1') of said corresponding signal (Sg1') received by the second antenna of said identifier (Id); - the identifier (Id) comparing said measured power (P1') with a threshold power (Ps), said threshold power (Ps) corresponding to a threshold distance (ds) from said first antenna which is smaller than the radius of a circle inscribed in the passenger compartment of the motor vehicle, said circle being centred on said first antenna; - said first antenna receiving, via the Bluetooth Low EnergyTM communication protocol, the result of the comparison between the powers P1' and Ps; - enabling the starting of the motor vehicle if the measured power (P1') is greater than or equal to said threshold power (Ps); - positioning said identifier (Id) at a reference position (Por) of the motor vehicle; - said first antenna being placed at a predefined distance from the reference position (Por); - adjusting the communication channel between the first antenna and the second antenna of said identifier (Id) with the first antenna on the first use of said identifier (Id) with the motor vehicle and/or on request, the adjustment comprising: ∘ transmitting, by means of the first antenna, a first calibration signal (Sgc) at the nominal power toward the second antenna; ∘ measuring the power (P2') of said corresponding reception signal (Sgr) received by said second antenna, and sending said measured power (P2') toward said first antenna; ∘ comparing said measured power (P2') with a theoretical power (Pt) corresponding to said predefined distance, using a regression curve (Cn) of power as a function of distance; ∘ determining whether there is an offset (Off) between said measured power (P2') and said theoretical power (Pt); ∘ if there is an offset (Off), modifying the nominal power of the first transmitted Bluetooth Low EnergyTM signal (Sgl) as a function of said offset (Off), or modifying the threshold power (Ps) as a function of said offset (Off). ∘ transmitting, by means of the first antenna, a first calibration signal (Sgc) at the nominal power toward the second antenna; ∘ measuring the power (P2') of said corresponding reception signal (Sgr) received by said second antenna, and sending said measured power (P2') toward said first antenna; ∘ comparing said measured power (P2') with a theoretical power (Pt) corresponding to said predefined distance, using a regression curve (Cn) of power as a function of distance; ∘ determining whether there is an offset (Off) between said measured power (P2') and said theoretical power (Pt); ∘ if there is an offset (Off), modifying the nominal power of the first transmitted Bluetooth Low EnergyTM signal (Sgl) as a function of said offset (Off), or modifying the threshold power (Ps) as a function of said offset (Off).