A thermo wire testing circuit, comprising: a current source terminal for supplying a test current to a first thermo wire via a first terminal during a test mode; a current drain terminal for receiving the test current from a second thermo wire via a second terminal during the test mode; a reference resistor for generating a reference voltage, which reference resistor is arranged in the current circuit of the test current; and a processing unit coupleable to the first and second terminals and to the reference resistor, and configured to compare a voltage drop caused by said test current between the first and second terminal with the reference voltage.