V50 L5-2.4L VIN 39 B5244S7 (2005)
Oxygen Sensor: Description and Operation
Heated Oxygen Sensors (HO2S)
Front 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).
The 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 in front of the three-way catalytic converter (TWC). This is so that the Engine Control Module (ECM) can continually check the
combustion so that lambda=1. lambda=1 is the ideal fuel-air ratio, with 14.7 kg air per 1 kg fuel.
The heated oxygen sensor (HO2S) uses current control 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 (HO2S) needs reference air from the surrounding
air. This reference air reaches the heated oxygen sensor (HO2S) via the air lines.
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).
The engine control module (ECM) can diagnose the heated oxygen sensor (HO2S). For more information, See, Heated oxygen sensor (HO2S)
diagnostic.
Vehicle Information and Diagnostics Application (VIDA) can be used to read off the calculated lambda value from the heated oxygen sensor (HO2S).
Center heated oxygen sensor (HO2S) (certain markets only)
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).
Some vehicles have 3 heated oxygen sensors (HO2S), front, center and rear.
The center heated oxygen sensor (HO2S) is the same type as the rear. However it has a different part number to differentiate it from the rear heated
oxygen sensor (HO2S).
The center heated oxygen sensor (HO2S) is used
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to provide the engine control module (ECM) with information about the remaining quantity of oxygen in the exhaust gases. This information is
provided more quickly than in vehicles with only a front and rear heated oxygen sensor HO2S)
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to allow quicker start of exhaust purification
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for regulation when the engine is under low loads.
The center heated oxygen sensor (as with the rear 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.
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
