Remove/install heated O2 sensor - AR07.52-P-5303CW

ENGINES 271 in MODEL 172, 204, 207, 212 

Shown on engine 271.8 

Fig 1: Identifying Heated O2 Sensor Remove/Install Components - Shown On Engine 271.8

Courtesy of MERCEDES-BENZ USA

Shown on engine 271.9 

Fig 2: Identifying Heated O2 Sensor Remove/Install Components - Shown On Engine 271.9

Courtesy of MERCEDES-BENZ USA

	Remove/install
	Risk of injury  to skin and eyes caused by handling hot or glowing objects.	Wear safety gloves, protective clothing and safety glasses, if necessary.	AS00.00-Z-0002-01A
	Risk of death  caused by vehicle slipping or toppling off of the lifting platform.	Align vehicle between columns of vehicle lift and position four support plates at vehicle lift support points specified by vehicle manufacturer.	AS00.00-Z-0010-01A
1	Raise vehicle
2	Remove rear section of the lower engine compartment paneling	Model 204
		Model 172	AR61.20-P-1105W
		Model 207, 212 Install engine compartment paneling only after engine test run.	AR61.20-P-1105EW
	Oxygen sensor downstream of catalytic converter (G3/1)
3	Unclip and disconnect electrical connection for oxygen sensor downstream of CAT (G3/1x1) on bracket	Unclip electrical line for sensor from bracket (1).
4	Remove oxygen sensor downstream of CAT (G3/1) from CAT (4)	Coat thread with paste.
			*BA14.00-P-1001-01A
		Paste	*BR00.45-Z-1005-06A
	Oxygen sensor upstream of catalytic converter (G3/2)
5	Unclip and disconnect electrical connection for oxygen sensor upstream of CAT (G3/2x1) on bracket	Engine 271.9: Unclip electrical line from bracket (2).
6	Unclip electrical line for oxygen sensor upstream of CAT (G3/2) on heat shield for the right engine mount
7	Remove oxygen sensor upstream of CAT (G3/2) from CAT (4)	The oxygen sensor upstream of CAT (G3/2) is a wideband sensor and therefore is extremely sensitive to the effect of applied forces. Pay attention to the following points otherwise the oxygen sensor upstream of CAT (G3/2) will be damaged: Engine 271.9: Do not pull out oxygen sensor upstream of CAT (G3/2) using pliers: just place with an open end wrench on the hexagon. When cleaning the thread, do not use any force (e. g. with pliers or vise) on the stem of the oxygen sensor upstream of CAT (G3/2). Engine 271.9: When replacing the oxygen sensor upstream of CAT (G3/2) the balance resistor (3) for the new oxygen sensor (G3/2) is already put on and must not be replaced (resistance depends on the sensor). Coat thread with paste.
			*BA14.00-P-1001-01A
		Engine 271.8	Fig 3
		Paste	*BR00.45-Z-1005-06A
8	Install in the reverse order
9	Attach STAR DIAGNOSIS and perform default initialization of the ME-SFI [ME] control unit	After replacing the oxygen sensor upstream of CAT (G3/2) A default initialization must be conducted using STAR DIAGNOSIS in the ME-SFI [ME] control unit under the menu item "Control unit adaptations" since the mixture adaptation of the ME-SFI [ME] control unit must be reset.
	Risk of accident  caused by vehicle starting off by itself when engine is running. Risk of injury  caused by contusions and burns during starting procedure or when working near the engine as it is running	Secure vehicle to prevent it from moving by itself. Wear closed and snug-fitting work clothes. Do not touch hot or rotating parts.	AS00.00-Z-0005-01A
10	Perform engine test run while checking the exhaust system for leaks

Fig 3: Identifying Box Wrench Bit (000 589 71 03 00)

Courtesy of MERCEDES-BENZ USA