A method for detecting an impending failure of a disk drive system. The method includes monitoring a signal from a magnetoresistive sensor for the presence of a negative signal spike. A negative signal spike can indicate that the carbon overcoat of the magnetic medium has been locally worn off. The resulting localized absence of carbon overcoat causes the magnetoresistive sensor to short to the magnetic medium. This causes a short, abrupt drop in voltage, which can be used as evidence of the localized absence of the carbon overcoat. If such a negative signal spike is detected, the user can be notified of an impending system failure. In addition to, or in lieu of, notifying the user of the impending system failure, the system can be automatically de-activated to prevent data loss and/or further damage to the recording system.