Apparatus and method for detecting metal disturbance during a medical procedure includes a probe having an insertion tube, a joint and a joint sensor, contained within the probe, for sensing a position of the insertion tube. The joint sensor has first and second subassemblies that are magnetic transducers. A processor is used for measuring force using the joint sensor, and has a threshold field value stored therein. The processor compares a sensed field value to the threshold field value and identifies a presence metal when the sensed field value is greater than the threshold field value.