A method to monitor and control the temperature of a sample holder of a laboratory instrument during execution of a temperature profile on the sample holder, the laboratory instrument comprises a sample holder with high temperature uniformity, a thermoelectric element which is in thermal contact with the sample holder, and a control device, wherein the sample holder comprises at least three identical temperature sensors, wherein the temperature profile comprises at least one set-point temperature (34, 40, 46, 52, 58), wherein the execution of the temperature profile on the sample holder comprises heating or cooling of the sample holder to the at least one set-point temperature (34, 40, 46, 52, 58) for a predefined time duration (36, 42, 48, 54, 60) and at a predefined time point (38, 44, 50, 56, 62), the method comprising the following steps (68, 70, 72, 74, 76, 78): a) the control device controls the thermoelectric element to heat or cool the sample holder to the at least one set-point temperature (34, 40, 46, 52, 58) of the temperature profile b) the at least three identical temperature sensors measure at least three actual temperatures of the sample holder and transmit the at least three measured actual temperatures to the control device c) the control device compares the at least three measured actual temperatures with a predefined maximum permissible temperature deviation range from the at least one set-point temperature (34, 40, 46, 52, 58) d) the control device calculates at least three temperature differences between each of the at least three measured actual temperatures e) the control device compares each of the at least three calculated temperature differences with a predefined maximum permissible temperature difference range f) the control device determines to continue the execution of the temperature profile on the sample holder if at least two of the measured actual temperatures are within the predefined maximum permissible temperature deviation range from the at least one set-point temperature (34, 40, 46, 52, 58) and if at least one of the at least three calculated temperature differences is within the predefined maximum permissible temperature difference range or the control device determines to abort the execution of the temperature profile on the sample holder if less than two of the measured actual temperatures are within the predefined maximum permissible temperature deviation range from the at least one set-point temperature (34, 40, 46, 52, 58) and if none of the at least three calculated temperature differences is within the predefined maximum permissible temperature difference range. a) the control device controls the thermoelectric element to heat or cool the sample holder to the at least one set-point temperature (34, 40, 46, 52, 58) of the temperature profile b) the at least three identical temperature sensors measure at least three actual temperatures of the sample holder and transmit the at least three measured actual temperatures to the control device c) the control device compares the at least three measured actual temperatures with a predefined maximum permissible temperature deviation range from the at least one set-point temperature (34, 40, 46, 52, 58) d) the control device calculates at least three temperature differences between each of the at least three measured actual temperatures e) the control device compares each of the at least three calculated temperature differences with a predefined maximum permissible temperature difference range f) the control device determines to continue the execution of the temperature profile on the sample holder if at least two of the measured actual temperatures are within the predefined maximum permissible temperature deviation range from the at least one set-point temperature (34, 40, 46, 52, 58) and if at least one of the at least three calculated temperature differences is within the predefined maximum permissible temperature difference range or the control device determines to abort the execution of the temperature profile on the sample holder if less than two of the measured actual temperatures are within the predefined maximum permissible temperature deviation range from the at least one set-point temperature (34, 40, 46, 52, 58) and if none of the at least three calculated temperature differences is within the predefined maximum permissible temperature difference range.