Remove/Install Nox Sensor - AR07.70-P-0001MRA

Engine 274.9 in model 205 

with code 920 (Direct petrol injection with stratified charging) 

except code 494 (US version) 

Shown on model 205.042 

Fig 1: NOx Sensor Components Location - Engine 274.9 In Model 205 With Code 920 / Except Code 494 (Shown On 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	Loosen right underfloor paneling		AR61.30-P-1001LW
2	Release and disconnect electrical line (1) on NOx sensor control unit (N37/4)
3	Unclip electrical line (1) from retaining clamps (2)
4	Remove NOx sensor control unit (N37/4) from undercarriage	The NOx sensor control unit (N37/4) with NOx sensor (N37/4b1) are one assembly part and can only be removed together. NOx sensor control unit on vehicle underfloor	*BA07.04-P-1003-01N
5	Unscrew the NOx sensor (N37/4b1) out of the exhaust pipe and close off threaded hole in the exhaust pipe with a suitable stop plug	: Coat thread on NOx sensor (N37/4b1) with hot lubrication paste.
		Paste, hot lubrication 1 kg, DBL 6879.20	*BR00.45-Z-1005-06A
		NOx sensor on exhaust pipe	*BA07.04-P-1002-01N
		Record plug	Fig 4
		Box wrench bit	Fig 3
6	Cover NOx sensor (N37/4b1) with a protective cover	When reusing the NOx sensor (N37/4b1).
		Set of protective caps	Fig 2
7	Install in the reverse order
8	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
9	Carry out an engine test run and check 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