A method of monitoring a heat exchanger of a vehicle, coated with an ozone-oxygen conversion material, including detecting the heat exchange medium temperature (tka) and heat exchange temperature (tprem) and plotting the values as a function of time, determining the area value (atka) of the heat exchange medium temperature, comparing the value of the heat exchange medium temperature with a setpoint value, repeating the foregoing steps if the sensed value is negative relative to the setpoint value, devising a quotient of the area values of such temperature, comparing the devised quotient with a defined setpoint range (RA) and determining whether such devised quotient falls within or without such defined setpoint range.