A method, consisting of acquiring signals,indicative of temperatures at respective locations in abiological tissue, from a plurality of thermal sensorsmounted on a probe in contact with the tissue,interpolating between the temperatures so as to produce atemperature distribution map, and displaying thetemperature distribution map on a screen. The method alsoincludes determining that at least one of the thermalsensors is a malfunctioning thermal sensor, and thatremaining thermal sensors of the plurality are correctlyoperating. The at least one malfunctioning thermal sensoris assigned a first arbitrary temperature and thecorrectly operating thermal sensors are assigned secondarbitrary temperatures. The method further includesinterpolating between the first and second arbitrarytemperatures so as to produce an error distribution mapindicative of a suspect portion of the temperaturedistribution map, and superimposing graphically the errordistribution map on the displayed temperaturedistribution map.
