Front heated oxygen sensor (HO2S), preheating
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2006 Volvo S80, 2005 Volvo S80, 2004 Volvo S80, 2003 Volvo S80, and 2002 Volvo S80. However, it is still accessible from the selected car via links, so may be relevant.
Checking that the heating circuit begins after dew point has been reached. The control module registers an electrical fault and checks the probe's λ value. A diagnostic trouble code (DTC) for a faulty signal is stored if the value deviates from 1 within a set time after the control module interprets that heated oxygen sensor (HO2S) preheating is not working.