ML 550 (164.172) V8-5.5L (273.963) (2009)
Oxygen Sensor: Description and Operation
GF07.61-P-3024MIG ME Oxygen Sensor Heater, Function
GF07.61-P-3024MIG ME Oxygen Sensor Heater, Function
- as of model year 09
Function requirements for oxygen sensor heater, general points
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Circuit 87M ON (engine control ON)
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Engine running
Oxygen sensor heater, general points
The oxygen sensor heaters bring the oxygen sensors (O2 sensors) up to operating temperature more rapidly. With controlled heating, they also prevent
damage to the oxygen sensor ceramics.
Oxygen sensor heater function sequence
The oxygen sensor heaters differ according to lambda sensor type. The function sequence is described in the following steps:
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Wideband oxygen sensor function sequence
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Non-linear oxygen sensor function sequence
Wideband oxygen sensor function sequence
The O2 sensor on the left and right upstream of CAT (G3/3, G3/4) are constantly heated while the engine is running to achieve their function.
Temperature control and temperature measurement (by measuring the internal resistance) is performed by special control electronics in the ME-SFI
[ME] control unit (N3/10)
Non-linear oxygen sensor function sequence
The oxygen sensor heaters for the LH and RH O2 sensors downstream of the CAT (G3/5, G3/6) are actuated by the ME-SFI control unit with a ground
signal.
To do this, the ME-SFI control unit (N3/10) reads the signal from the coolant temperature sensor (B11/4).
When the exhaust system is very cold (while condensation is present), the oxygen sensor heaters are switched off to prevent damage (due to thermal
shock).