O2 Sensor light on 190E 1992 - PeachParts Mercedes-Benz Forum

meltedpanda · #1 10-04-2006, 07:45 PM

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

mbdoc · #2 10-05-2006, 08:08 AM

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.

meltedpanda · #3 10-05-2006, 10:08 AM

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

meltedpanda · #4 10-09-2006, 06:10 PM

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?

meltedpanda · #5 10-10-2006, 10:46 AM

is it on the exhaust manifold/pipe

tvpierce · #6 10-10-2006, 04:45 PM

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

meltedpanda · #7 10-10-2006, 04:50 PM

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

danwatt · #8 10-10-2006, 08:25 PM

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.

tvpierce · #9 10-11-2006, 11:13 AM

Quote:

Originally Posted by meltedpanda

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

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

mbdoc · #10 10-11-2006, 11:49 AM

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!

meltedpanda · #11 10-11-2006, 02:09 PM

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

mbdoc · #12 10-11-2006, 03:12 PM

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!

meltedpanda · #13 10-11-2006, 04:21 PM

crystal clear now, thanks MBDoc

meltedpanda · #14 05-09-2007, 08:24 PM

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

MTI · #15 05-10-2007, 02:01 AM

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.