We report the isolation of a new defect inn‐type silicon following room‐temperature electron irradiation. Using deep level transient spectroscopy (DLTS) combined with minority‐carrier injection at 250 K, we show that the DLTS peak usually ascribed to the phosphorus‐vacancy pair hides a signal arising from this defect in its stable configuration. We find that the defect can exist in three other configurations which can be individually studied by DLTS. It is proposed that this defect involves a lattice vacancy and a phosphorus atom, plus a third unidentified defect or impurity.