Rear heated oxygen sensor (HO2S)
WARNING: This page is about a different car, the 2004 Volvo S40, 2003 Volvo S40, 2002 Volvo S40, 2001 Volvo S40, and 2000 Volvo S40. However, it is still accessible from the selected car via links, so may be relevant.
Measurement range 0-5 V
Voltage from the rear heated oxygen sensor (HO2S).
Oscillates between 0 and 1 V when the three-way catalytic converter (TWC) is cold (>300°C).
Stabilizes at 0.2-0.7 V when the three-way catalytic converter (TWC) is at operating temperature (<300°C)