O2 sensor replacement, how often?
 

Hi All,

According to the Maint. Sheet from the CD, it's required that I replace my O2 sensor every 30k mi. This right?


thanks,

Judging from past & plenty experiences with O2 sensors, I would suggest that you can double that. ;)

Changed at 55K...

My mechanic hooked up the reader and checked the response time. He checked at 45k and noticed they were getting slow. Finally at 55k, the check engine light came on and they were replaced. Fairly starightforward DIY job on the C280. Took me about 1 hour. Each one cost about $90. Get the OEM sensor, the universal ones you need to splice the connectors, not a good thing to do.

thanks,
 

thanks... since I'm at 70K now and don't know if it's ever been replace... will do so shortly...

thanks,

PS> What are the symptoms of failure of the sensor if any

On the W201, the odometer tripped the O2 sensor light at approximtely 60K miles. Symptoms of a totally failed sensor: fuel fouled spark plugs (wet); really bad gas mileage; running extremely rich. The sensor doesn't really affect start up much, since it only comes into play once it reaches operating temp in the exhaust system, so initially the car may seem fine, but a minute or so later, you should notice. For a sensor that's marginal, the symptoms may be less dramatic.

spark plugs...
 

Thanks for the info. Last time I changed my plugs 1 or 2 were kind of wet. I was thinking it might be a prob with fuel injectors. Didn't realize the O2 sensor might have something to do with it. Will check plugs as I have new ones on hand and start from there....


thanks,

In the early days of O2 sensors, manufacturers were concerned about their life and didn't want to get stuck with replacement under the 50K mile emission warranty.

My erstwhile '84 190E 2.3 had a light that the odometer activated at 30K miles to notify the owner that a change was required. If done, the tech removed the bulb from the light. There was no other subsequent change recommended - just the one at 30K miles. When my light came on I removed the bulb. When I sold the car at 49K it still had the original O2 sensor. It ran normally and passed emissions.

The maintenance schedule on my '88 190e 2.6 recommends replacing the O2 sensor at 60K and there is no reminder light like on the '84, but my CA model has some health checks and diagnostics including the O2 sensor. At 75K miles my O2 is original, and it functions properly based on a duty cycle check and scope check of the O2 sensor output about a year ago.

Bottom line is tha O2 sensors are getting more reliable, and there is no need to change them at an arbitrary mileage. You can wait until you get an O2 sensor fault code if your model has O2 sensor diagnostics, and if your car fails emissions, a check of the duty cycle and O2 sensor output is warranted. If you don't have the knowledge and equipment to check these functions and don't want to pay to have it done (assuming you can find a competent tech who can actually perform these tasks) then you can change the O2 sensor at an arbitrary mileage or if you fail an emission test, but you may be replacing a perfectly good sensor.

Duke

sensor
 

Got it... I'll just wait for the symptoms since it's like $100... hehehe

thanks,

I have never replaced an O2 sensor on a preventive maintenance basis. My 300E has over 265,000 miles and it is original. Engine runs perfect.

If it ain't broke, don't fix it.

Good luck,

Larry, thats my experience witht he 91 300E. It had 120k when we bought it and now has 230k with the same O2 sensor.

What kind of mileage do you get with your 5spd?

Haasman

My '91 300E has started to have a rough idle recently. I just checked the plugs and it's obviously running rich.

The car has 65K on it. I have to take it in to have some work done so I guess I'll have them replace the 02 sensor. Is there anything that needs to be checked or adjusted when the sensor is changed on this vehicle?

BTW, I've been looking at buying a new E-Class so putting a few hundred into my pristine 300E is peanuts compared to buying a new car. The difference in license plates here in Arizona is about $700 between my 300E and a new E320.

Thanks in advance,
Bud

Bud,

Email me please.

Haasman

I just sent you a message.