In a method for assisting a driver of a vehicle, a closed loop control device and/or open loop control device is switchable into multiple warning stages such that: if at least one temperature value measured by a temperature sensor exceeds a first defined threshold value, the closed loop control device and/or open loop control device switches into a first warning stage in which it is indicated to the driver to stop the vehicle within a defined period of time and/or within a defined section of road and/or that the driver is not to exceed a defined speed value. If the measured temperature value exceeds a second defined threshold value, greater than the first threshold value, the closed loop control device and/or open loop control device switches into a second warning stage in which it is indicated to the driver that the driver is to stop the vehicle immediately.