An implantable medical device having a sensing module and a control module is configured to receive a cardiac electrical signal and sense events from the cardiac electrical signal received via electrodes carried by a medical electrical lead when the medical electrical lead is coupled to the implantable medical device. The control module coupled is configured to detect non-sustained tachyarrhythmia (NST) episodes based on sensed event intervals and determine if the sensed event intervals during the detected NST episode satisfy oversensing criteria. If the oversensing criteria are satisfied, the control module determines whether the detected NST episode satisfies non-lead related oversensing criteria and withholds a lead integrity alert when the NST episode meeting the oversensing criteria is determined to satisfy non-lead related oversensing criteria.