BMW N55, Manual, Page: 96 / 100

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N55 Engine
Oxygen sensor before catalytic converter
The Bosch oxygen sensor LSU ADV is used as the control sensor before the catalytic
converter. The abbreviation LSU stands for “Lambdasonde Universal” and ADV for
“Advanced”. The function is similar to that of the LSU 4.9 oxygen sensor and is therefore
described in detail in the E71 X6 training material under “N63 engine” available in TIS
and ICP.
The oxygen sensor before catalytic converter (LSU ADV) offers the following advantages:
• High signal stability specially during turbocharged operation due to low dynamic
pressure dependence.
• Increased durability due to reduced pump voltage.
• Increased accuracy (by a factor of 1.7 compared to LSU 4.9).
• Ready for operation in < 5 seconds.
• Greater temperature compatibility.
• Improved connector with more effective contacting properties.
The LSU ADV has an extended measuring range, making it possible to measure
precisely from lambda 0.65. The new oxygen sensor is ready for operation faster so that
exact measured values are available within 5 seconds of start up.
The higher measuring dynamics of the sensor makes it possible to more effectively
determine and control the fuel-air ratio separately for each cylinder. This results in a
homogeneous exhaust flow that reduces emissions while also having a favorable effect
on long-term emission characteristics.
Oxygen sensor after catalytic converter
The oxygen sensor after catalytic converter is also known as the monitoring sensor.
The familiar Bosch LSF 4.2 monitoring sensor is used.