Why would O2 sensor get this color??
10-11-2011, 01:44 PM
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Why would O2 sensor get this color?? Been pulling a 0402 code for a few years now (
). Though it's a bank 1 cat error, the cat was changed. The lower (after cat) O2 sensor was then changed. Still got the 0402. FINALLY changed the upper (pre-cat) O2 sensor and the error cleared and stayed clear.
After pulling the old (109,000 mile) upper sensor, I found it had a strange red color. I don't think it's rust, though may be, but it's a very hard coating, almost like it was powder sprayed and baked (which I guess it actually was if you think about it...)
Just wondering what would cause this type of coating. Fuel? Additives? Other lubricants leaking into the cylinders?
The aft sensor looked normal (black), and when looking down the cat, it is quite clean....
Thanks!!
). Though it's a bank 1 cat error, the cat was changed. The lower (after cat) O2 sensor was then changed. Still got the 0402. FINALLY changed the upper (pre-cat) O2 sensor and the error cleared and stayed clear.After pulling the old (109,000 mile) upper sensor, I found it had a strange red color. I don't think it's rust, though may be, but it's a very hard coating, almost like it was powder sprayed and baked (which I guess it actually was if you think about it...)
Just wondering what would cause this type of coating. Fuel? Additives? Other lubricants leaking into the cylinders?
The aft sensor looked normal (black), and when looking down the cat, it is quite clean....
Thanks!!
10-12-2011, 09:38 PM
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its the fuel.
i work for benz dealer here and we get secondary air injection system codes regularly, the o2 sensor reaction time slows (thus setting the code during a self test of the sec air inj system), EVERY single one that has the code gets pulled out is red. i dont know where these people buy fuel, but its not every car.. im guessing some people buy gas from one brand station while others buy from others.
i work for benz dealer here and we get secondary air injection system codes regularly, the o2 sensor reaction time slows (thus setting the code during a self test of the sec air inj system), EVERY single one that has the code gets pulled out is red. i dont know where these people buy fuel, but its not every car.. im guessing some people buy gas from one brand station while others buy from others.
