Rafael Grullón

A few days ago I got a CEL warning. Read the codes and came out as the oxygen sensor 2/ bank 2. My mechanic replaced the right side (passenger side) after catalytic sensor, cleared the codes and after a few miles the light was on again.
I think we changed the wrong O2 sensor.
I´ve done an extensive search on this forum as well as in the web, some people say bank 2 is left (driver) side, other say is right (passenger) side.
Does anyone for sure know which one is which?

ruffrob

I had my O2 sensors replaced back in April of 05,since they presumably work together,you should replace both at the same time.

Rafael Grullón

Ruffrob, thanks for your reply.

I´m, in fact, replacing both O2 sensors because the tread on the one wrongly removed was damaged a bit and didn´t want to plug it on the left pipe for not damaging the tread in the pipe itself, but the question remains the same. Which one is which? Bank 2, right or left?

On the other hand I somewhat disagree with you about changing always the other side sensor as well, because it is known that sensors could be bad for different reasons, and many of them, if motor is well mantained could never need to be replaced in the car´s life. If your statement is right, then all sensors should be changed, once one go bad.

Richard Galing

Bank 2 is the right side (passenger side), I'm quite certain!

Rafael Grullón

If that is so, why the right side bank of cylinders (in V configuration engines) is call bank 1 and the left is bank 2?

The hesitation in my mind comes because a lot of people, as yourself, in this forum and in the web also think that passenger side is bank 2.

If we could find a book or something related to this issue.....

Thanks

purplegrog

have you tried calling a dealership and asking to speak to the shop foreman? they're usually pretty helpful.

Richard Galing

I'll confirm this information with my MB tech on Monday...Stay tune.

Rafael Grullón

Someone in other forum sent me this link where explains clearly where is bank 1, 2 and oxygen sensors location and names.
The thing is now where is cylinder 1 in MB with V configutration, I think is in the right side of the car, but that´s easier to find out.

http://www.asashop.org/autoinc/june2002/techtips.cfm

Rafael Grullón

I found it!
Cylinders in MB V engines go 1,2,3 on the right side and 4,5,6 on the left side for V6.
In V8 is 1,2,3,4 on the right side and 5,6,7,8 on the left.
That means bank 1 is on the right side.
We changed the wrong O2 sensor.

Taiwanese

How many oxygen sensors are there in a 98 E320?

ohlord

two pre cat and 2 post cat,autohausaz.com has them.What codes are you reading? no reason to replace all of them unless you want to make them a maint item,which some people do.and bank 1 is the left side as you face the engine from the front of the car...........ohlord

Taiwanese

ohlord,

Thanks. I am just going to do all 4 because the car has 90,000 miles.

ohlord

above as to bank 1 and bank 2 the shop looks at the engine from the back end,since real people look at it from the end that they are looking at the pass side on the left is the one with cyl 123 front to back bank 1,and the right side has 456 bank 2,,same with the w210 v8 left 1234,right 5678.
ohlord
and get the proper o2 socket and work safe and slow and read the directions you get with the sensor...........

azurE430

the right side of the car is always the right side. the left side is always the left. its based on if you were sitting in the drivers seat, not standing in front of the car. so the head on the pass side and the four cylinders are right bank. so which one are they saying is bank 2?

ohlord

much explained above,the shop would call the right side from in the car which would be to the left side as you looked into the hood.open the hood stand in front of the engine,reach out with your left hand and touch the side that is on the left,that is bank 1,the first cylinder is plug one,v6 1,2,3 v8 1,2,3,4.....

on the attached link,the line drawing of the engine below the very cool video. the side closest to you is bank 2 cyl 456 on the v6,5678 on the v8.the far side is 123 the 1 being the first cyl in the firing order
http://w210.pietrzyk.net/enginesm112_general.htm
side with oil filter bank 2

and that link pretty much puts to rest the L6 v.s. V6 power claims,less friction,more balanced engine and >100 lbs. weight savings is alone worth the equivalent of more than 12h.p. on the V6 as compared to the L6 more h.p. more TQ. at a much broader tq. curve l6 peaked at 3750 rpm V6 torgue curve greater all the way from 3000-4800 rpm FYI

that guy 1

bank 1/2 changes sides w make model and year there is no thing 100% designating left and right except wich cyl is furthest in front but they still dont mean 1 or 2 indefinitly mechanic ase cert in engine repair 7 yrs exp.

Colin Roberts

probably if it's a 4cyl 2, 6cyl 4, 8cyl 4 BUT if you had a CL600 v12 there are 14 when I had mine back in 2005 they were Ł114 each...that was an expensive service...

Colin Roberts

Is that looking at the engine from the front of the car towards the engine or from inside looking forward...I know it sound daft but it does make a diffrence...lol

Colin Roberts

Is this looking at the engine from the front of the car or from the back.

glhansenjr

Anybody have a document showing which side is Bank 1 and Bank 2 for an M156 engine?

Instead of saying "right" or "left" side, can we designate "driver" and "passenger" side, assuming these are American cars with driver steering wheel on "left".

davmil2002

Ha. Good idea (diagram)

glhansenjr

Anybody?

Some people say passenger side is Bank 1, others say driver side is Bank 2.

Anybody have an actual ALLData or WIS document for the M156?

Joe's E350

Amen! Let's assume American/left-hand driver cars and simply state passenger or driver's side.