What is the replacement interval for O2 Sensors?

In this particular case I'm wondering if it's time to change mine in my M103, but I'm sure it's not too different most other FI Benzes.

The only rumor I've heard is 30k mi, but my books say nothing....

__________________
Currently:
1972 350SL Euro 4spd
1973 BMW R75/5
1981 BMW R80GS
1995 FZJ80 with OM606 Conversion In Progress

To the best of my knowledge the Oxygen sensor(s) should be replaced every 60,000 miles.

__________________
Fred Hoelzle

220 000 kms=140 000 miles.Third owner.
original o2 sensor,
passed emission test 2 yrs ago.

Is it time to change out the Oxygen sensor before the next emission test?

No dash lights has come on.

__________________
Tom 2010 C250 4-matic Sport (Canada)

O2 sensors slow down with age.. To keep things running optimally I like to change them out every 30-40K.

I've also taken to updating our 3 wire O2's w/ 4 wire. Run the extra ground to the negative battery terminal and you'll have an O2 that responds quicker then the 3 wire.

Jonathan

__________________
Blue Ridge Mercedes
Jonathan Hodgman
http://www.blueridgemb.com/
Enthusiast Service, Restoration & Tuning.
Follow Us on Facebook!
Located in the Atlanta area
Specializing in all pre and post merger AMG's including Hammers and DOHC M117 engines.
Mercedes Repair Atlanta

Cool tip, Jonathan. I'll remember that.

__________________
Manual Tranny or Bust!

Jonathan,

Do you have a Bosch # for the four wire? I need to pick one up ASAP, my only garage time for the next month is this weekend.

Thanks.

__________________
Currently:
1972 350SL Euro 4spd
1973 BMW R75/5
1981 BMW R80GS
1995 FZJ80 with OM606 Conversion In Progress

I am not sure that O2 sensor should be changed unless it stops to work. The voltage from the O2 sensor should alternate within a range (use AC voltmeter). If this is occuring, it is o.k., if it is pinned on low or high side, i.e. you see a constant voltage (use DC voltmeter because AC meter would read zero) then it needs a replacement. For eg. my car has >350K miles and it is the same O2 sensor. Had to replace the catalytic converter because that will clog over time.

__________________
Saumil S. Patel

O2 sensor replacement interval varies depending on the model and era. They come in 3 versions - 30k, 60k and 100k. Yours is probably a 60k - but the site below will say for sure. Periodically Bosch runs an advertising campaign on changing out O2 sensors periodically as a preventive maintenance item - on the grounds that fuel economy is improved. I have a tendancy to forget about it and replace it only upon an O2 fault code. But these days it wouldn't take much a fuel economy improvement to pay for a new sensor.

http://www.boschautoparts.com/Resources/VehiclePartFinder/

Never seen a more incorrect statement.
O2 sensors not only switch ( high/low ) voltage signal, but also switch at a certain rate.
This is called " Cross Counts ".
As a sensor ages, it will " slow down ".
When it reaches that stage, fuel economy and exhaust emissions generally suffer.
Maybe if you had changed your O2 sensor at say 100 k miles or sooner, who knows, may not have plugged your catalytic converter.
O2 sensors are a Maintenance item, i.e. part of a major tune-up.

__________________
2007 C 230 Sport.

It may be a mantainence item BUT in my 350K, not once did the O2 sensor light indicate to me that the O2 sensor was bad. And not once did the car fail an emission test. Just lost power gradually likely because of oil burning, and inspite of continuously degrading CAT, the emission was just fine. Plus when I tested the sensor output, it did modulate the output between 0.1 and 0.9V that mercedes manual says is a test for a good O2 sensor. At the same time I agree that the rate at which the O2 sensor responds to changes in oxygen is critical, and if this response rate is not adequate then the output of the oxygen sensor will not be accurate and the computer will make an inaccurate mixture adjustment. BUT if the lag is too big, at some point the O2 sensor output will go out of the limits. And if the voltage remains in the correct range, I am not sure if the problem is that significant.

__________________
Saumil S. Patel

What model year is your car ?
I bet you will not get away with it on an OBD II compliant ( 1995 + ) car.

__________________
2007 C 230 Sport.