Remove/Install Oxygen Sensors - AR07.04-P-0021MRA

Engine 274.9 in model 205 

Engine 274.9 in model 253 

Shown on ENGINE 274.9 in MODEL 205.042 

Fig 1: Upstream And Downstream Oxygen Sensor Components Location - Engine 274.9 In Model 205 (Shown In Model 205.042)

Courtesy of MERCEDES-BENZ USA

	Risk of burn injuries,  suffocation and poisoning when working on the exhaust system and the components connected to it. Risk of suffocation and risk of poisoning caused by inhalation of gaseous and solid components of the exhaust. Risk of poisoning  caused by skin contact with solid components of the exhaust.	Wear protective clothing and safety glasses. Use the extraction system. Move people out of the hazard area.	AS49.00-Z-0001-01A
	Information on preventing damage to electronic components due to electrostatic discharge		AH54.00-P-0001-01A
	Notes on avoiding damage through contamination and foreign objects		AH00.00-P-5000-01A
	Note on calculation of tightening torque when using insertion or socket tools with various effective lengths		AH00.00-P-0015-01CW
	Remove/install
1	Remove air filter housing		AR09.10-P-1150MRA
2	Release and disconnect electrical connection for oxygen sensor upstream of CAT (G3/2x1)
3	Unclip electrical line for oxygen sensor upstream of CAT (G3/2) from brackets
4	Remove oxygen sensor upstream of CAT (G3/2) and close off threaded hole in CAT using suitable stop plugs	Coat thread with hot lubrication paste. Oxygen sensor upstream of catalytic converter	*BA14.00-P-1005-01A
		Paste, hot lubrication 1 kg, DBL 6879.20	*BR00.45-Z-1005-06A
		Box wrench bit	Fig 3
		Record plug	Fig 4
5	Cover oxygen sensor upstream of CAT (G3/2) with a protective cover	For reuse of the oxygen sensor upstream of CAT (G3/2). Set of protective caps	Fig 2
6	Release and disconnect electrical connection for oxygen sensor downstream of CAT (G3/1x1)
7	Unclip electrical line for oxygen sensor downstream of CAT (G3/1) from brackets
8	Remove oxygen sensor downstream of CAT (G3/1) and close off threaded hole in CAT using suitable stop plugs	Coat thread with hot lubrication paste. Oxygen sensor to catalytic converter	*BA14.00-P-1002-01A
		Paste, hot lubrication 1 kg, DBL 6879.20	*BR00.45-Z-1005-06A
		Box wrench bit	Fig 3
		Record plug	Fig 4
9	Cover oxygen sensor downstream of CAT (G3/1) with a protective cover	For reuse of the oxygen sensor downstream of CAT (G3/1). Set of protective caps	Fig 2
10	Install in the reverse order
11	Read out and erase fault memory		AD00.00-P-2000-04B
	Risk of accident  from vehicle starting off by itself when engine running. Risk of injury  (bruises and burns) resulting from working on the engine while it is being started or when it is running.	Secure vehicle to prevent it from starting off by itself. Wear closed and snug-fitting work clothes. Do not touch hot or rotating parts.	AS00.00-Z-0005-01A
12	Perform an engine test run; check engine for functionality and exhaust system for leaktightness

Fig 2: Identifying Set Of Protective Caps (001 589 00 91 00)

Courtesy of MERCEDES-BENZ USA

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

Courtesy of MERCEDES-BENZ USA

Fig 4: Identifying Record Plug (129 589 00 91 00)

Courtesy of MERCEDES-BENZ USA