XC70 AWD L6-3.2L VIN 98 B6324S (2009)
Caution! The air lines for the heated oxygen sensors (HO2S) must not be trapped or damaged in any way. The connectors for the heated
oxygen sensors (HO2S) must not be greased under any circumstances. The oil in the grease would disrupt the reference air and the function of
the heated oxygen sensors (HO2S).
Front heated oxygen sensor (HO2S) is used to provide the engine control module (ECM) with information about the remaining oxygen content of the
exhaust gases before the three-way catalytic converter (TWC). This is so that the engine control module (ECM) can continually check the combustion so
that lambda=1 is achieved. lambda=1 is the ideal fuel-air ratio, with 14.7 kg air per 1 kg fuel.
The heated oxygen sensor uses current regulation and its signal characteristic is linear. With a linear signal characteristic, the amplitude of the signal
curve is low when changing the oxygen content in the exhaust gases. The probe consists of a preheating element (see "Pre-heating heated oxygen sensors
(HO2S)") and the actual lambda sensor. The lambda sensor is an oxygen sensitive ceramic body consisting of zirconium oxide. The control module
supplies power to the ceramic body, which reacts to the oxygen content of the exhaust gases. This in turn affects the signal to the engine control module
(ECM). In order to determine the oxygen content in the exhaust pipe, the heated oxygen sensor needs reference air from the surrounding air. This
reference air reaches the heated oxygen sensor via the air lines.
There are two front heated oxygen sensors; one for bank 1 and one for bank 2.
The heated oxygen sensors (HO2S) are diagnosed by the engine control module (ECM) and the signals from them can be read off. For further
information, see: Heated oxygen sensor (HO2S) diagnostic See: Powertrain Management/Computers and Control Systems/Description and
Operation/Heated Oxygen Sensor (HO2S) Diagnostic
The control module can be used to read off the calculated lambda value from the heated oxygen sensor (HO2S) signal.
Rear heated oxygen sensor (HO2S)
Caution! The air lines for the heated oxygen sensors (HO2S) must not be trapped or damaged in any way. The connectors for the heated
oxygen sensors (HO2S) must not be greased under any circumstances. The oil in the grease would disrupt the reference air and the function of
the heated oxygen sensors (HO2S).
Rear heated oxygen sensor (HO2S) is used to provide the Engine Control Module (ECM) with information about the remaining oxygen content of the
exhaust gases behind the three-way catalytic converter (TWC). This information is used by the Engine Control Module (ECM) to check the function of
the three-way catalytic converter (TWC). This check is carried out when the conditions for the catalytic converter diagnostics have been met. Rear
heated oxygen sensor (HO2S) has no direct effect on regulation of the fuel/air mixture. However the Engine Control Module (ECM) uses the signal to
optimize the signal from the front heated oxygen sensor (HO2S).
For further information, see: Three-way catalytic converter (TWC) diagnostics See: Powertrain Management/Computers and Control
Systems/Description and Operation/Three-Way Catalytic Converter (TWC) Diagnostics
The heated oxygen sensor (HO2S) uses voltage control. The signal characteristic is binary. With a binary signal characteristic, the amplitude of the
signal curve changes considerably when changing the oxygen content in the exhaust gases. Otherwise its components and function are the same as the
