O2 Sensor light on 190E 1992
 

OK back on my friends car now. Her light is on and I have searched and am lost in the mix of "forget it" switch it out, costs too much ect ect
First off - where is it located?
easy fix?
do I need to plug in for engine test?
ignore?
unplug?
Help out an old diesel guy...thanks

That is a "California" thing...either remove the bulb OR the computer that turns the lamp on!

Computer is located next to the console on passenger side under the under-dash panel...retangluar box 3x4x1.

it is from California, bought new there, so disconnecting sounds like the way to go, I like that - thanks:wacko:

OK bulb is next to impossible to get to,no make that impossible, and I cant find little black box
Can I just unplug the sensor, OH and BTW where is that located?:D :confused: :D

is it on the exhaust manifold/pipe

The 02 sensor is located on the manifold. But you can't fix this problem by simply unplugging it. The 02 sensor is not an emissions part per se, it's an integral part of the fuel injection system.

Jeff Pierce

so you are saying replace, vs ignore, disconnect?
Hmmm ....MB DOC has some credentials after his name :D

Replace the thing... but first read the code to verify it's the o2 sensor.

Try resetting the light first... maybe it won't come on again.

But really, the light is there as a diagnostic aid, telling you there is a problem with the car. Fix the problem.

MB DOC is far more knowledgable than I (that's not even close)... but our two responses are not contradictory.

He said you could unplug the lamp or the computer that turns the lamp on. You cannot simply unplug the O2 sensor and expect the car to run properly.

The lamp and computer to turn it on must be CA emissions specific -- and are not integral to the operation of the car. They are simply electronic "reminders" for you to replace the O2 sensor before it goes bad.

Respectfully,

Jeff Pierce

TV is correct....I suggested that the COMPUTER that controls that light for CALIFORNIA be disconnected!

that is a very simple & takes less than 15 minutes... Removal of passenger under dash panel & carpet & foot rest panel.....O2 sensor computer looks just like the fuel pump relay...

Disconnecting the O2 sensor will only create problems!

:confused:so I got this right, disconnect computer and leave current O2 sensor in place or disconnect and replace O2 sensor?
Sorry I seem to be such a dimwit

The O2 warning lamp comes on for that California car by MILEAGE & not for any other reason...

Disconnecting the O2 mileage monitor has no effect on emissions OR operation of the O2 system. And is not required in any state but California!

crystal clear now, thanks MBDoc

No I have not done it yet, have been at work on my 71 and forgot about it fixing another problem and remembed this one.
I tool carpet out, under a plastic foot panel is 2 boxes one silver and one black, lot of wires in to them am I in the right place?
or is it under glove box area, anyone have the part number so I disconnect the right box:wacky:

There were two "versions" of the O2 sensor warning lamp in the W201. Up until 1987, the bulb was switched on by a trip pin on the odometer that turned on the bulb at roughly 60K miles. There was no system to reset the switch, so as a result, the only way to turn off the light after replacing the O2 sensor was to actually remove the bulb from the right side of the instrument cluster.

On later models, including yours, there is a computer module that triggers the light, but not based on mileage, but based on the signal from the sensor. It still means that you have to replace the O2 sensor, but there should be a reset button on the top of the module to reset the dash indicator.

Find out the real problem. Read the MB defined duty cycle and perform the repair.

This is a really simplistic system.

thanks

will a universal bosch three wire work (or similar) or do I have to get an MB version? I notice the 3 wire do not have the MB connections but they could be spliced in easily.

The Bosch sensor for the 5.0L Ford Mustang V-8 is the identical sensor, but the molded plug needs to be spliced on.

In researching an O2 sensor for my 1991 300CE, I see the Bosch unit for my car ($$$) and also the less expensive Ford sensor. The wire lead on the Bosch one is quite long versus the much shorter lead on the Ford sensor. Is it the idea that you cut the lead off your old sensor and splice it on the new Ford sensor? Is matching up the wires obvious?


Thanks,

glenmore
1991 300CE
2000 C280
1990 LS400

There are more than a few threads in Mercedesshop's archives about the Ford Mustang sensor, but the answer to your questions is yes, you splice the leads from the old Mercedes sensor onto the new Mustang's.

The sensor for the 1990 Ford Mustang 5.0L V8 (Bosch PN 13942) has metric threads (with a little Anti-seize already on them), and virtually is the same sensor unit. The only differences between the Ford sensor and the Mercedes sensor is 1) the end connector and length of wire; 2) name of the car it goes into - based on the salesman's computer database; and 3) PRICE!!!!! If you're buying the sensor from a non-Ford parts dept (Autozone, NAPA, PepBoys, etc.) they may tell you they have more than one sensor for the application, but the only difference is the wire lead length, which you're not going to use anyway. Just get the cheaper one. Also, some Mustangs had two sensors, so don't let the parts guy sell you two for your non-existent pony car.

The sensor in the W201 is the three-wire type, (with two white heater wires), To fit, cut off the Ford connector and solder the existing Mercedes connector on to it (while matching wire colors), and install. .