o2 sensor
 

I am going to change my o2 sensor on my 1988 560sl
Do I have to reset anything ?
In the shop cd it says something about a indicator control module # n441/1
Where is that ?
It had to be reset once because its got 78,000miles
Any help would be appreciated greatly
Is there any trick way to get out one rusted sensor without destroyng
the exhaust system?

Why are you replacing the O2 Sensor?

Merry Christmas,

I felt like the sensor has never been replaced
So instead of guessing I got a Mustang sensor for $38
This way I would have a good base line
I just bought the car this year

There is absolutely no need to replace an O2 Sensor as a preventive maintenance item. If it starts setting a code and turning on the check engine light, then it is time to replace it. Otherwise there is absolutely no gain to be had by replacement.

I have one car with 186,000 miles with original sensors, another with 278,000 miles with original sensor. They both run great and get the same mileage they always have.

If it ain't broke don't fix it. You stand a bigger chance of causing problems by changing it, especially since you will be rewiring the Ford sensor. Put the new sensor in your toolbox and save it for the time when you might need it.

Good luck,

so what your saying is that even though the manual recommends changing the O2 senson (at least in my 89 300E) every 60,000 miles you dont really need to. the senson isnt made by mercedes... so they would have no reason to want you to change just so they could make more money. i think it is great that your cars have gone as long as they have without changing the O2 sensor but i am sure that with your expertise you have taken extrememly good care of your car. with that in mind i tend to believe that most people dont take care of their cars as well as you do... leading me to believe that the best course of action would be to follow the recommended maintainence schedule as i am sure the car in question was not taken care of as well as yours.

as for the guy putting a Ford o2 senson in a benz... shame on you! spend the money... get the bosch. there is a reason these cars cost so much brand new... and the best way to keep them running that way is to replace the repaired parts with OEM or aftermarket parts made for a benz. a ford part on a benz... WHAT IS THIS, THE JAGUAR FORUM!?

That is why I am replacing it
o2 sensors will change readings because there old .
I spent 30 plus years in maintenance in a large plant
And predictive maintenace always worked better than reactive maintenance
I wish the last owner took that approach to some items I had to replace
Also look at the bosch web sight and see the gas savings on replaceing old tired 60,000+mile o2 sensors
Besides why would bosch and Mercedes say to change it ,
if it were good ???
They now from experence that they are in the fail zone period.
I guess its pay me now or pay me later deal.
Some times we get away with it , but I am going to keep this car so might as well get the full time out of the sensor
By the way besides the connection and the $100 price difference they are the same o2 sensor. There both bosch sensors
Just that one fits the Mustang
Read old Posts on it.

Mike,
Of course Bosch wants you to change it every 60k. The reason the light comes on to change the sensor every 30k is part of the Federal clean air requirment. The law required the sensor be changed automatically at 30k with instructions to remove the bulb on early models. I go along with Larry on leaving it alone with a slight modification. The sensor could get lazy and respond slowly which might not trigger the MIL (malfunction indicator light), but reduce performance. In fact if you have a Federal car, you almost have to cut the sensor wire to trigger the light. The early OBD I systems wouldn't trigger the light for any other system failure except on California models. You can check for a lazy sensor with a lambda tester without replacing if it checks out ok.

Peter

You guys have a good answer
I guess I will leave it alone
If its not going to make the car run any better
Thanks again

I agree with Larry and Peter. The 02 sensor change interval of 60K is triggered by emission and emission warranty considerations. The one time change recommendation at 30K miles for early eighties cars got MB off the hook to have to buy O2 sensors for customers before the 50K emission warranty ran out. Interestingly this change was ONLY recommended at 30K miles - NOT EVERY 30K miles. After the initial change at 30K there was no recommendation to change it as PM ever again. This was then replaced by the recommended 60K PM change, which is arbitrary.

02 sensors probaby have more service life than originally envisioned, and I see no need to change them until they fail or cause emissions/fuel economy problems.

You can eavesdrop on the O2 sensor output by pulling the single pin connector under the carpet enough to attache a scope lead, the voltage should swing in a sharp jump between about 0.2 and 0.8 at a with a period of about 0.5 to 2.0 seconds. Test at idle and about 2000 RPM. If it performs to these specs the O2 sensor is very likely okay and does not need replacement.

You can run this test periodically to determine the health of the 02 sensor or if you fail an emission test or notice reduced fuel economy.

Duke

At 58k miles I changed the 02 sensor on my E320 wagon. No check engine light came on, but it was getting suddenly 15mpg on the highway from normal 25-26. Ordering the MB part proved it was expensive, and worse, out of stock for 3 months. Went to Autozone and purchased the Bosch "Universal" for $60-70. Got the old one out of the dual exhaust pipe connectors with lots of WD40, vice grips, and warming up the engine while it was jacked up. Screwed the new one in, did the minor rewiring job, mpg is now back at 26 and the exhaust smells better.

My 1992 Range Rover has 189k miles on it with original sensors. No Check Engine light. Mpg is 12/15 city/ highway EPA. Actually now gets 10/15. Some last longer than others. Not running the right grade of gas can cause premature failure. Our 96 Explorer 4.0 V6 replaced an 02 sensor (tripped check engine and bad mpg at 80k) now needs the other one at 135k. Check engine has been on forever, who cares, mpg isn't suffering so bad. 1995 Range Rover 4.0 had 02 sensors replaced under recall in 2000.

I agree: 60k recommendation is probably for emission reasons.

I was getting a rich exhaust before very black sooty tail pipe
not running great , very spongy off idle
Checked duty cycle on injection
found it to be rich
Addjusted duty cycle at tower 3/8 turn lean to help condition
Car runs great.
Thats when I started to check ou o2 sensor
Notice it looked original
So I figured this may help
but after reading I wonder if it would be worth wasting my time
The only question I have is if the o2 is reading (example .2 low)
This is sending back to the computer a .2volt lower than it should
Then the injection is makeing the mix that much more richer
Does this make sense
or should I just go to the bar tonight and forget trying to fix things that are already fixed???

information in the post
 

You really should include all of that information (running rich, etc) in the very first post in the future. That way you will get the best input. If you had said that you were running rich and worked-around it by adjusting air/fuel for example, then that would have triggered different input. I have a 1984 380SL and I bought a brand new Bosch sensor online for $18, same as original. Check what Fastlane here sells it for (see the link above.) If not there are other sites on the Internet that sell them economically like autopartsauthority.com but we should support FastLane if we can since they host this site for us.

This is getting as controversial as " oil change intervals ". ;)
In my experience, an O2 sensor can be almost as unpredictable as a lightbulb.
Some seem to run forever, some not.
A good O2 sensor can be observed by watching the " cross-counts ", i.e. how many times it switches from rich to lean, in a given time.
Duke 2.6 correctly pointed this out earlier.
As an O2 sensor ages, it will get " lazy ", i.e. instead of, say 10 cross-counts/second, it slows donw to, let's say 5 crosscounts.
This may not result in the illumination of the Check engine light, but can have an affect on emissions & fuel economy.
Bottom line..........it's up to you to decide. ;)

My original question was about tripping a relay when I take the o2 sensor off
So i did not bore everyone with why I was changing it
Sorry for the confusion
Still was informative to me
But still have not found an answer if there is a(oxygen sensor relacement indicator contol module n44/1 ) as the cd from MB says there is
no location nada?

it's actually funny, for the 380SL manual
 

I seem to recall reading that the procedure to reset the o2 sensor light was, believe it or not, to remove the lightbulb! Obviously not much of a solution. This is from memory..

On your dash, use a flashlight (or not if the symbols are clearly legible) to light up the warning lights. On some cars, particulary earlier ones, I believe that there might have been a "Lambda Sensor" warning light. As to the reliability of these, I don't know. There shouldn't be anything to reset-just plug in (or rewire) the new sensor. The engine reads the correct inputs and adjusts the fueling system accordingly.

Correct! The O2 sensor light illuminated on the dash of my erstwhile '84 190E at 30K miles. I asked the dealer how they reset the light. The answer was remove the bulb, which I did without replacing the sensor.

I sold it at 49K, and it passed its title transfer emission test - no problem.

Duke

[QUOTE=manny]A good O2 sensor can be observed by watching the " cross-counts ", i.e. how many times it switches from rich to lean, in a given time.
Duke 2.6 correctly pointed this out earlier.
As an O2 sensor ages, it will get " lazy ", i.e. instead of, say 10 cross-counts/second, it slows donw to, let's say 5 crosscounts.
This may not result in the illumination of the Check engine light, but can have an affect on emissions & fuel economy.
Bottom line..........it's up to you to decide. ;)[/QUOTE

I believe ten "cross counts" is too fast. The typical "period", which would be two cross counts should be about one second. If it's slower than two seconds the sensor may be getting lazy.

The actual response time of the sensor is about a tenth of a second, but the system richens very slowly so it doens't get ahead of sensor response time.

This is my understanding based on reading about O2 sensors, but I'd welcome anyone's comments who has good info as I have found it difficult to find information on O2 sensor failure modes.

Slow response time is one and I also suspect that they may drift off calibration, but have not been able to confirm.

Duke

on my 190e2.6, the engine began sputtering for no apparent reason and at unpredictable times, when the weather was cold. This was so difficult to diagnose that I left the car at the MB service center. They were able to reproduce the problem, which they traced to a faulty/malfunctioning O2 sensor. This, without the "Check Engine" light coming on, and well below the 60k interval since the time it was last replaced.

Replacing the O2 sensor fixed the problem. The issue here is that the sputtering engine problem can be a safety issue, because it happens with no warning. It almost left me stranded in the middle of an intersection in the lane of oncoming traffic, as I was making a left turn. I had to nurse the car to a safer location until it recovered.

This sputtering engine problem happened again years and many kilometers later, again, without the "Check Engine" lamp coming on. I immediately asked my MB service advisor to have the O2 sensor replaced. They placed a note on the service sheet that it was done at the request of the customer.

Duke 2.6

In my " simplified " explanation earlier, I just tried to convey a message to " the people ", as to what can be expected from an O2 sensor.
Of course the cross-count timing is exaggerated, but the principle of " healthy " vs. " lazy " sensor activity should be understood. ;)
Btw, the average DVOM is only averaging the voltage output readings from the sensor, so while it may show activity, it is not necessarily " real time " information.

Good point. You need a scope to observe real time O2 sensor behavior. I don't have one, but I have a friend who does, and I'll borrow it to eavesdrop on my O2 sensor's behavior before I go in for my emission test that's due in a couple of months.

Duke

Mike,
I'm assuming that when you say you are reading .2 O2, you are talking about voltage at sensor and not gas reading at tailpipe, because that is a perfect tailpipe reading. If you read a constant .2 volts in open loop, you need to replace the sensor. Don't worry you won't trigger any lights.

Peter

I just put that as an example of a voltage
The question I had was really how do you Know the calibriation of the sensor
If in 1988 the .5 volt at a certain co
Today may be in 2004 .2 volt with that same sensor?????
So thats were I felt just starting with a new sensor would eleminate
any guess work of getting wrong reading to the injection system
I am just asking If this makes sense
The sensor is so old I can't get it loose anyway
I am going to hit It with the torch next

If the duty cycle wanders around a little at idle or "hunts" up & down once your O2 sensor is warmed up, it's working. No need to change & no improvement expected from a change. Take a break, have a beer instead.

I appreciate all the help from everyone
I feal better now understanding how it works
I like your idea on the beer can't go wrong with that move.
This sight has a great bunch of people
cheers!!!
Mike

Mike,
It doesn't matter how old the sensor is. It should always be around .5 volts in either open or closed loop. The only difference being that in closed loop it should sweep back and forth. It would take awhile to explain how the system works, which is why I suggest you do an archive search. There is enough info there to keep you up all night. Or is that nite?

Peter

I finaly got some time to check the voltage at the o2 sensor
disconneced it and took some readings
Voltage was at .2 vdc and some times lower under .1vdc
if I raced the engine nit went up once in a while to .8vdc
But not all the time especially after running for a while
Seems like when it got hot it stayed at low voltage

Injection check

I also checked voltage at termanal x11 terminal 2 & 3
getting .6 v at idle
But racing engine I was getting 12.5 vdc
What gives???

Sounds like IF you have a 3-wire sensor, the heating element is gone ( the 12 volt side ).
On the old, single wire sensors, you had to rev the bejeepers out of the engine to heat it up.
O2 sensors start putting out a valid signal at @ 600 degrees.
Many engines will idle at about 450 - 500 deg. ;)

Thanks for the help
I will try to get it out .

One other question I have about cam timming
I check stretch today
Drivers side looks good but Pass side showing 7 degree at the crankshaft to get the marks to line up
Is that normal to have the driver side right on and the other cam out that much
Should not the driver side be out say 2 degrees fom stretch
Or is the cam just out and do they have an offset key for the cam???
or do I need a chain
I Know the guides are due at 78,000
Any help is appreciated

This may sound dumb, but what is the O2 sensor and what is it's purpose. If it fails what happens? What if the O2 sensor cable is pinched into, will the car start? Does anyone have a picture of the sensor and cable? Where is it located? :confused:

I'll give you the simple version.
The oxygen sensor is screwed into the exhaust, where it monitors the presence or abscence of oxygen.
Based on the information from this sensor, yhe vehicles computer will either richen or lean the air/fuel mixture to the engine.
A failed sensor will illuminate a " check engine " light, your fuel economy will be decreased, accompanied by an increase of exhaust emissions.
It has absolutely no effect on the startability of an engine. ;)
Btw., if you have a diesel, forget everything I said. :D