O2 Sensor

[babybenz]

Ok, you 1.8 owners.

Anyone of you know where the O2 sensor (or connector) is found on my 1991 190e 1.8 RHD (Euro)?

On other forums, they keep mentioning the passenger footwell area.

I've found thick wire insulation going across the footwell from left to right, and it exits the car thru' a rubber grommet near the tranny tunnel.

I split the insulation and found six wires, 2 x purple/white, black, black/red, light brown and yellow grey.

Looking under the car, the wires travel under the car thru ' a black corrugated flexible hose and goes to the tranny.

There, a smaller corrugated hose branches off from the bigger one and disappears behind the tranny.

I think that of these 6 wires, some are for the tranny and others for the O2 sensor.

Anyone know?

Btw, I made a DIY wire harness at the footwell area so I could extract voltages from the 6 wires with respect to ground.

Engine on at 83 deg :

Purple/wht 1 = 0.03V
Purple/wht 2 = 0.03V
Black = -0.04V (neg?)
Light brown = 0.04V
Black/red = 13.54V (obviously battery voltage at idle)
Yellow/grey = 0.04V

Cheers.

 

[DavidBlake]

The sensor is screwed into the exhaust downpipe, ahead of the CAT.
I think on your model the connector is either in the drivers footwell on the inside, or underneath attached to the floor pan, should be obvious when you have found the Lambda sensor.

 

[babybenz]

Thanks, David.

Interesting that I have been told again and again that the connector of the O2 sensor can be found on the passenger footwell area under the carpet.

Perhaps, that's where they are on US cars...

I'll check it out.

Thanks again.

 

[babybenz]

Can't find it, yet...

Lifted the car and looked along the exhaust manifold, downpipe and all the way back to the tail pipe.

Nothing!

Gave the local dealer my VIN number and they confirmed an O2 sensor for my car (1.8 RHD), so it has to have one - but can't find it.

Looked at my friend's '90 124 and also can't find it.

Looked at the driver's side footwell (inside) - nothing.

Whazzup???

I wonder if any 1.8 owners out there have ever replaced their O2 sensor and would know coz we have the same spec car here.

Thanks for your help.

 

[Arnie]

There are different standards for the connector; for your car it may be OBD-I (On-Board-Diagnostics-I), while the latter standard is OBD-II. I think that only in the more recent models (OBD-II), the location of this socket has been standardised to be in the driver's footwell area. There should however, be a multi-pin socket somewhere in the egine bay that provides all the signals (used for the MB diagnostics computer). I think that the OBD standards have originated from Californian legislation for emissions control and checking.

BTW, the sensor itself should be located just ahead of the catalytic converter (from the downpipe) and sticking out at right-angles. It may also be found somewhere on the exhaust manifold. It's about 4" long and usually bright-plated with a heat-shielded lead attached to the end. Its signal is fed to the car's ECU, MB diagnostics socket and, if it has one, the OBD socket.

 

[babybenz]

The OX!!!

Damn...

Have to look again.

Thanks, dude.