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  #1  
Old 12-08-2004, 09:15 AM
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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?

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  #2  
Old 12-08-2004, 10:05 AM
LarryBible
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Why are you replacing the O2 Sensor?

Merry Christmas,
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  #3  
Old 12-08-2004, 10:20 AM
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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
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  #4  
Old 12-08-2004, 10:38 AM
LarryBible
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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,
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  #5  
Old 12-08-2004, 11:41 AM
89 300E
 
Join Date: Nov 2004
Location: Greensboro, NC
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Quote:
Originally Posted by LarryBible
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!?
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  #6  
Old 12-08-2004, 11:51 AM
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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.
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  #7  
Old 12-08-2004, 12:40 PM
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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
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  #8  
Old 12-08-2004, 12:48 PM
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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
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  #9  
Old 12-08-2004, 12:55 PM
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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
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  #10  
Old 12-08-2004, 01:40 PM
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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.
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  #11  
Old 12-08-2004, 02:10 PM
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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???
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  #12  
Old 12-08-2004, 03:36 PM
SL Owner
 
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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.
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  #13  
Old 12-08-2004, 03:55 PM
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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.
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  #14  
Old 12-08-2004, 04:12 PM
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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?
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  #15  
Old 12-08-2004, 04:35 PM
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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..

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