Changing the o2 sensor

[bass1175]

Anyone changed this sensor if so please provide any tips, whether I would need to lift the car up or if I can get it from under the hood. Thanks

[Merc600sec]

Underside..lift the car , the O2 sensor is in the exhaust before the cat.And yes you can do it yourself.. not difficult remember to disconnect before you remove it do not use any sealing compound when fitting.. and only remove the cover on the sensor just prior to putting it in the hole..

[Brett San Diego]

you will have a pre-cat and a post-cat O2 sensor on the exhaust for each bank of cylinders.

Easy to swap out using Rhino Ramps. The threads may be corroded and stuck in the exhaust pretty good. Disconnect electrical connector, put a 22 mm box-end wrench on the sensor. Use a cheater bar or hit the wrench with a hammer... whatever it takes to break it loose. Maybe a good soaking with penetrant will be helpful.

Brett

[bass1175]

Thanks for the tip, I tried several times to go on ramps but they start rubbing on the bumber, They have newer plastic ones that I want to purchase that are less steep.

I found universal boosch sensor that comes with stripped colored wiring, to connect to the old harness. Theyre 120 bucks cheaper, would you guys trust these?

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&ru=http%3A%2F%2Fsearch.ebay .com%3A80%2Fsearch%2Fsearch.dll%3Fcgiurl%3Dhttp%25 3A%252F%252Fcgi.ebay.com%252Fws%252F%26fkr%3D1%26f rom%3DR8%26satitle%3D8028697126%26category0%3D%26f vi%3D1&item=8028697126

[dm567]

Does that mean there are four O2 sensors for a V8 s500?

Are there two cats? I have not looked.

How do you know which one is Bank 1 Sensor 1

Thanks,
dm

[rsmcmahon]

On early model W140's V8s there is only 1 O2 sensor.

What model and year is your W140?

I would trust the Bosch universal O2 sensor, but I might not trust my ability to solder and seal the wiring to the old connector. If you try it, you might want to use the uncoated, barrel wire connectors with solder. Also use the heat shrink cable tubing to seal your connection.

[dm567]

Its a 2000 s500 and I have learned that there are two sensors, one before each cat.

Another benzworld member probably diagnosed my problem and I may not need to change the O2 sensor yet. Engine missfires and O2 sensor trouble codes may have been due to using regular instead of the required premium gasoline.

However, I'm glad you told me about the generic bosh O2 sensor. When the time comes I think I'll try it and save a bunch.