Preheating, rear heated oxygen sensor (HO2S)

Checking that the heating circuit begins after dew point has been reached. The control module registers electrical faults in the front probe. The control module measures the resistance in the heater element so that the probe temperature (which is continuously compared with a temperature model) can then be calculated. A diagnostic trouble code (DTC) for a faulty signal is stored if the temperature in the probe is lower than a designated value in the temperature model.