Abstract In some automotive applications, high negative bias is used to faster switch off n-type devices. This exceptional operative gate voltage at relative high temperature can induce instability of device parameters (e.g. threshold voltage, transconductance, saturation current, etc. In this work we will show that positive charge trapping generated under exceptional negative bias can induce large threshold voltage shift. Even if the effect can partially recover during the standard operative condition, nevertheless large Vth, shift are still present and can affect the correct functionality of the device.